My biggest concern so far is the exploitability of Firewine, Smokepowder and Oil Barrels. While they may be rather heavy, collecting and depositing them in the Camp is fairly simple.
Once you run into a difficult'ish encounter, such as the Githyanki or the Hag, you can simply hide outside their view, place barrel after barrel after barrel in the middle of their position without them reacting, then finish them off with an Alchemist Fire, Fire Arrow or Fire Bolt to bypass the entire encounter without ever being in danger.

My second biggest concern would be the exploitability of stealth vs. the AI in its' current state. To stress the absolute broken state of this, I just finished completing an entire playthrough, killing every single thing that I could find while exploring the entire map with the exception of the encounter on the boat while sailing to the end of the Early access content. I did so without a party, twice, playing a Rogue Thief and then a Dex based Fighter. The simple tactic, hide, activate turn-based when approaching enemies, fire from high ground when possible, then walk half my movement away and end the turn. Repeat.
The AI will default to "Planning Next Move" in 99% of the cases without the enemies ever thinking to take cover, group up, search for me or flee. Granted, a few encounters I cheesed even harder - a handful of which I used the Barrels mentioned above and another I used the wannabe Beholder in a necklace. Oh and lastly on the theme of AI, walking through loading doors resets battle entirely making a handful of locations even easier to beat.

Now, in terms of requests I would really like to see;
The Crossbows be affected by the Loading property that disallows multiple shots from it during a single round. A heavy crossbow can deal way too much damage in the hands of a fighter with access to action surge in a single round.
Bless, Bane and other spells that target a number of creatures to allow the player to actually select the targets and not just have it randomized in an area.
Add the Word of Radiance cantrip for clerics.
Remove the ability for Wizards to learn class specific and divine spells from scrolls.
Add an interface that shows details on progression for a given class and subclass - i.e. when I create a Fighter I would like to be able to see what I can expect from the coming levels.
Show DCs, Dice rolls and bonuses instead of adjusting the DC to your bonus, I know it might seem more complicated, but I think it highlights what you are good at and what you are not more clearly.
Add an option to see dice rolls on attacks etc. instead of or in addition to x%

My biggest, most precious dream for Baldurs Gate 3 is the inclusion of the Import/Export/Pre-generate Character options which were found in the old Baldur's Gate games. Second to that would be an option to Roll for stats rather than Point Buy, or possibly add 2 more options for Point Buy, one with less points and another with more - catering for those who want a harder or easier game.