-Only six classes. 5e is babbys' first arrpeegee and they couldn't even put in all the classes? Hard fail. BG 1 had all the 2e base classes. This is pretty much non-negotiable for a D&D game so I don't know who to be more disappointed in, Larian or WotC.
-Le opening cinematique. I have an issue with D&D games specifically that pit you against out-of-depth monsters at low level but use dumb plot contrivances to help you win. There is no reason a bunch of level 1 newbies would stand a chance against mind flayers or cambions or have any way to survive the crash.
-Companions. If you can't put a full breadth of companion classes/alignments in the game, then you have the obligation to make the available companions non-insufferable. BG1/2 did it right--evil party members cause drama, good ones don't. The evil guys were better in combat as a tradeoff. In this game everyone causes drama. Oh look, the only healer is an evil cunt who hates the only fighter who is an arrogant cunt. Lovely. The only rogue is a fucking vampire. Why would I want ANY of these losers? (the mage is actually alright)
Ugh. Custom built party or bust.
-Character building. When I pick my class, can I see what skills and abilities I'll get when I level up? Nope. How should I pick between Fighter and Ranger, what are the tradeoffs? Warlock vs Wizard? No idea. If you don't own a 5E PHB, lol sucks 4 u. Plus who knows how they actually implemented the rules. When you level up the game doesn't make it clear you can even pick stuff. It just says "You get spells X Y Z," you have to click on the customize button to bring up the full spell selection. WTFFFFFFFFFF. I didn't realize my ranger could even pick from more spells at first. Don't make my fucking picks for me game, that's the entire fun of leveling up.
-The biggest problem: Larian world design. It's so myopic. WTF is going on? I just fell out of the sky and I'm on a beach. Time to go find a town. Except you can't, you're stuck in this tiny narrow path. God dammit, have these assholes played ONE fucking tabletop session in their lives? I have never played a D&D game that started with so little freedom, besides dungeon crawlers. Even ToEE let you visit a few places.
BG1: Whole sword coast to explore
BG2: Whole Athkatla to explore
BG3: Small beach to explore, plus the nearby woods.
If they follow the OS2 path, then each chapter will be this smallish area of narrow paths and encounters strung between inane side quests and "humor." Mixed with 5E's flaccid combat and non-existent character building, I can't picture the game as being anything other than a meandering, dull chore.