I am a long-time CRPG player who got my start with the original Baldur's Gate saga, but have also played all of the other Black Isle/Obsidian games and their spiritual successors made by Bioware (The Dragon Age trilogy and the Mass Effect Saga). I have also played 2nd, 3rd, and 5th edition Dungeons and Dragons and am a long-time fan of the game. I was very excited to hear BG3 was finally happening! I had never played a Larian game before, but after my first playthrough I enjoyed it well enough that I purchased both of the Divinity: Original Sin games and have been enjoying those as well. I figured it was high time I live up to my responsibility as an early access player to give some of my thoughts and feedback on the game so far from the perspective. There's a lot to unpack, but here are my thoughts on the companions so far. I am writing this just after the first patch that has addressed them, but based on my experience in the first month or so of early access. I'll rank them in order of favorites, and then add a bonus entry and some final big picture thoughts.
1) Shadowheart is by a lot my favorite party member so far. I certainly don't mind her mysterious personality- it makes building a friendship with her more interesting and rewarding. While she's an "evil" character there is a complexity to her, and she never seems quite truly evil, and I think having complex characters like this does a great service to the gaming community and the world. There is also a bit of tragedy inherent in the Sharran faith, and it is no doubt tragedy and trauma that shaped Shadowheart to be who she is. It would be unrealistic for a character like her to be too soft and reasonable. I'd also love to see different ways her character might develop because of her relationship with the main character. One could see her getting colder and more reserved to Shar, or possibly following some sort of redemption path and converting to Selune. These types of paths with characters are the thing that made companions so successful in prior RPGs, and I hope that Larian takes this into account as they go forward. I know that Larian has changed the companions somewhat, and I hope that in the bigger picture they haven't altered Shadowheart too much. The only thing I objected to was just how intense the rivalry with Lae'Zel was, and how just about anything that got approval from one party got disapproval from another. This was so extreme that it was pretty much impossible to have them both in your party, which is a shame since they are my two of my favorite characters. From a development standpoint you generally want to give players more options rather than fewer, and this seemed to close down paths rather than open them up. There was also no in-game reason why they hated each other SO much. I actually support the rivalry on a smaller scale because people often times simply don't like each other, and there does seem to be something in Shadowheart's past that makes her dislike Githyanki. Nonetheless, if this rivalry has been muted so that its possible to make a party with both, I can definitely commend and support that change!
Mechanically speaking, she's also the most useful companion. She obviously can serve as primary healer in a party, but can also be a tank and can provide tons of support to roguish activities through her trickery domain- a must in a party without a rogue or rogue-like character. She could so serviceable melee attacks, has good ranged attacks with her cantrips (and at least one good nuke spell), and can take a bit of punishment with good armor and a shield. While the upcoming nerf to her strength will limit her utility with traditional melee weapons, that just opens up the option to use finessable weapons and ranged weapons, to sneak around more, and perhaps have an even stronger build in the long run, so I support those changes as well.
2) Lae'Zel is also a really great character with a lot of complexity, and one who is rewarding to build a relationship with. It makes sense that she is a bit bossy and domineering, she comes from an extremely martial culture with a strong chain of command, and she has by far the most knowledge and experience of Mindflayers and their parasites, so it makes sense that she has impatience with the contrary thoughts of those with almost no experience of these things. She's also a great combination of mind and might, and I think its great in conversations how equally passionate she is about libraries and martial prowess. Too often in RPGs characters tend to one side or the other, and its great to have a character that doesn't really fit any of those boxes. There also seems to be value in the exchanges of culture the main character has with her, and that adds another layer to everything which is really great. Once again, the intensity of the rivalry with Shadowheart needed to be balanced/nerfed, but I don't think too many other changes to her character were necessary.
Mechanically speaking Lae'Zel is a star, though I definitely fell into the pitfall of building her less optimally at first! She's a fierce frontline fighter which everyone needs, but her ability to be an Eldritch Knight gives her a ton of flexibility and utility, which I found fun to play.
3) Gale is apparently one of the most popular characters and I see why! As someone who has played the original Baldur's Gate games many times, he is the character who most reminds me of the feel of the characters in that game. One great thing about BG was the quirky, fun characters. Minsc was for good reason the most popular non-player character of all time, and in order to better service those of us who played those games it is key to include some characters who remind us of those. He is definitely one of the more benevolent/good characters as well, though not too much so, and I think he's a great fit. I could comment more, but it seems like everyone loves him and Larian knows it, so there's no need to say too much more!
Mechanically Gale does die a lot, as confirmed in gameplay data and my own experience. That being said, while he is a bit of a glass cannon, he puts in work when he's up and is worth protecting. As long as he isn't dead, I can count on him to close out a fight with the greatest D&D spell of all time- Magic Missile.
4) Will is an important character to have in the party, and a likable, though not overly interesting one. He is the one truly, good noble character in the game. Of course, he has to have all sorts of emo demonic baggage because he is a warlock and because that is in fashion. He actually reminds me a lot of Valygar from BG2, which I suppose is a good connection with the earlier games. Personally I'd of taken Keldorn or Nalia as my static good character over Valygar, but that's just personal preference. I think he is fine and there does seem to be some potential for interesting stories involving Mizora later. I do wonder if there is an evil option where you kill Will and take Mizora in his place (she is featured in all the promotions for the game despite not being included in early access at all). If there is only one sixth party member I'd pick Karlach over Mizora personally, but it is an interesting potential development.
Mechanically Will is a good second caster who can also fulfill roguish functions if you build him that way. I like that he can misty step into or out of trouble, or to gain the high ground for stronger spell attacks. He's a great contributor to a party while being less mandatory than other characters.
5) I don't really understand or particularly like Astarion, though I am trying. It starts off pretty badly. Why he is he putting a knife to my throat, and why is Shadowheart just standing there watching. I know she and I just met, but we do have a working alliance and she probably would at least say something. Then all of the sudden were buddies? Its just too much and is not realistic. He doesn't really make any more sense later in the plot. I am cool with complexity, but he doesn't really seem to have much of a personality other than being a vampire, liking freedom, and other vampire fetishy stuff. Shadowheart is mysterious and hard to understand, but I can easily describe what her character is like and why she is that way. I can't really even describe Astarion- he's kind of just code. I think he has the potential to be a fun character if he was just written a bit better, but he needs a lot of work and a clearer direction.
Mechanically I expected him to be terrible, because in every computer D&D game ever made until now rogues have been both terrible and necessary. You had to have them because only rogues could open locks and disarm traps. Yet they were otherwise a waste of a party slot, so you would level Imoen as a Rogue to four, put all of your points into locks and traps, and then Dual her to mage so she'd be useful. Yet in the partial playthrough I did with Astarion he often outkilled the rest of the party, usually by do sneaky, roguish things! Kudos to Wizards for making rogues both unnecessary (since other characters can now do locks and traps) and better. And huge, huge kudos to Larian for making them good for the first time ever in a D&D CRPG by giving a lot more freedom to solve problems in creative ways. Now, if we could only improve his personality we'd really be winning.
6) Karlach- Karlach is not yet a recruitable character, but dialogue suggests she could be, and I really, really think that she should be made a playable companion. And we shouldn't have to wait till Baldur's Gate either- no one wants to change their party much later in the game. While she's only around for a short time she has super fun personality, and we really need another character like Gale. Recently Larian has responded to feedback about characters by softening them. I really don't think that's the answer- with the exception of nerfing the Shadowheart/Lae'Zel rivalry I think they are great. The problem is just that we need to complement the moodier characters with more fun, light-hearted characters like some of the ones we loved in the original games. Gale is that character with flying colors, and Karlach could be too. I especially like that she seems pretty optimistic and determined despite having fought in the Blood War. Things can only go up, right! I do hope that she gets put into the final game as a full character.
Finally, I have one high-level thought about how these characters will develop in the coming acts. In Larian's prior hit, the game was designed so that you could play as one of their characters, though the option existed to play a new one. The option to play as these characters is currently being planned, and while I always applaud more options, it does worry me. One of the great values of these characters in Bioware games was that your character's relationship with these characters could change their path, and they could change the main characters. When the game is designed around being these characters, there are limits to how each relationship will develop. In BG2 Viconia could be redeemed and change alignment or stay bad. In mass Effect you could kill Wrex or save him, and you had to make the brutal choice between Ashley and Kayden. Most players of these games are going to want to make their own character, and they want their choices to matter for these characters, as well as for these characters to influence them. Its fine to allow players the choice to be these characters, but I hope in development its viewed as the alternate option rather than the main path.