Ok, so first of all: I am HUGE fan of DOS2. I beat that game like 3 times and I had blast playing it. It was my fav RPG in last years with Witcher 3. So this is not because I don't like DOS2 system/world/mechanics.
This is because I wanted to play DnD. I am playing Table RPGs for 15 years now and for last 3 years I DM and play DnD 5e. I was really excited to play BG3 and really happy that it's Larian that will make it. But I was hoped to play almost 100% 5e system. Maybe 95% as some things can't be that easy put into cRPG.
But currently game is too much like DOS2. And I really don't like it. I feel "cheated" (strong world but hear me out first) that I was supposed to play DnD, not DOS2 1.5. I know it's EA, and I understand game can still be changed/adjusted so I take my chance here to post feedback and hope that Devs will hear me out.
So:
1. Ground elemental effects SHOULD absolutely be not part of DnD game. 5e is specific system that was designed in a way where lasting effects on ground (like Entangle, Mist, Could Kill, Storm Sphere, Spike Growth etc.) require a magical caster and concentration. Because they can be very powerful tools when you combo them with some other spellcasters, melee, grapplers etc. In BG3 this makes tons of spells dull. It's better to just place fire effect on ground from Cantrip and hold enemy with another party member there, than use higher level spell. Not only ground effect IGNORE AC (which is BIG deal in DnD system) but also deals DoT damage (which is also big in 5e system and effects like that require concentration, are in higher slots, like Heat Metal and are mostly single target). Simillar are other elemental effects on ground. They disbalance gameplay, they are easy to exploit and they are against core rules/mechanics of 5e. I would much rather have them removed and make spells do what they do in books so when AOE ground effect happens - it's more signifact and also makes spells feel unique - than having elemental ground spam again. This is not DOS2. It's DND. DnD doesn't need ground element effects, it has spells for that (like Fire Wall, Wall of Ice, Wall of Force, Sickening Radiance and many more).
2. Lowering AC and increasing HP of monsters is not good idea. They have that AC for a reason in 5e. This is to make sure that magic spells that ignore AC (Fireball, Lightning) or can damage high AC enemies (Heat Metal) or control enemies with high AC (Hold Person) are needed and are important in case where melee classes struggle. This is team-based system. AC is for a reason, so Fireball hitting group of enemies with AC 16 on level 5 will be very impactfull. Lowering that AC to 12-13 allows melee to just cut through them with eas (they can kill 1-2 enemies per turn) which makes spells like Fireball very very weak. Not to mention that increasing HP also makes spells like Fireball/Lightning etc. weaker as DEX save already cuts damage in half.
5e went through play-tests and that amount of AC and HP of enemies when compare to melee classes and spells are there to balance it out. This change is ABSOLUTELY not needed. You already have balanced system and play-tested in years. There is not place here for experiments that destroys that balance.
Also argument "less frustrating with misses" is stupid. Misses are part of d20 system. That is the system. You hit or miss. This is not DOS2 where you hit all the time and you balanced game around enemies HP/Shield/Armor bars vs DPS of players- this is not that system!
Also misses should be part of lower levels. Low levels should feel hard and frustrating because that is part of DnD system. Also - you can offset that with giving players options to get more magical items, like weapons +1/2/3, Belts of Strength etc.
Please remember that 5e is designed to be PERFECTLY viable for melee classes (when it comes to AC/HP vs hit chance/damage) without ANY MAGIC ITEMS AT ALL. Giving players a lot of magic items in 1-10 levels in 5e will already make them much better than system recommends to any adjustment to AC/HPs of enemies frtom 5e books is not needed at all. It will only cause never ending cycle or chantes/nerfs/balance patches while you have already handed to you on table a perfectly balanced system (well, of course there are less balanced things, that that is unavoidable in RPGs).
3. Beginning is little too much for 1st level characters and party members you meet - it's very unrealistic for such low level character to survive all that high-level maiheim around. I think character needs level 3 boost so it feel less anti-climatic. Remember that DnD is from "zero to hero". You don't start as hero with 8 HP
. I would tone down the beginning.
4. Alignments are big part of 5e system. They should have impact and be more important. It's not DOS with it's fluid personality system. Please remember that.
5. You have to make a decision - do you want to go down in history as devs that finally after many years made "another successful DnD cRPG" or devs who were afraid that that won't be enough and you need to also cather to your DOS2 fans and makes sure game looks simillar so they will buy product too. Please realize that some of us DnD fans were waiting very long to play another DnD cRPG. And we want to play that - DnD. It will also prove that DnD is great system for making cRPGs. But it will not happen if you will try to sneak in your favourite mechanics from DOS2.
Divinity system already had it chance and success. And I am happy for it. I will definitely play another Divinity Original Sin game, where I will expect and enjoy all DOS-specific mechanics. You will have chance to play with it as devs again, really. You will make another DOS game.
But please, make this one a DnD game. DnD deserves to be put into cRPG. It doesn't need to be mixed with another system. If there is any system that was tested enough in history of RPGs - that is DnD. And you already have huge DnD fan base. It will be enough, trust me.
Thanks for hearing me out. Love you Larian!