Yeah I'm enjoying what is available so far. The combat is pretty good, but I do hope they make some tweaks to make it more in line with regular 5e rules; I'm not really a fan of Larian leaving in so much of their combat stuff from games like DOS2 and having "house rules" that seem ridiculous (like lobbing heal potions around like healing grenades). The difficulty seems fine to me, and I'm certain they will have options to make it both less and more difficult for full release.
The companions are pretty good. I mean I strongly dislike some of them just because I don't like their personalities, but that is not a flaw with how Larian has done them. It is good that they give them plenty of flavor with their personalities. I am however worried about them making the companions too important, to the point where it feels like your own custom character is taking a backseat in the story compared to Larian's own origin characters. That would be a huge mistake if they don't remedy that situation before release, in my opinion.
Have a great day !
