If I loved DOS2 but not either of the Baldurs Gate games, would I like this?
It's basically DOS3 with a Baldurs Gate setting in, as Burns said, a more rigid DnD engine. BG games are great because of the story in them. Mechanically they're not the best (though exceptional when the first released), and CRPGs for a long time went the BG method of active battle with pause. Pillars of Eternity added turn based only as a Kickstarter goal I think, but was never really made for it. Pathfinder 1 added it later too, though it was more developed than in Pillars. Pathfinder 2 had it from the start as an option, but still designed as real time with pause. I love the Pathfinder games (while never having beaten them), but enjoy the combat far more in DOS than Pathfinder / Pillars of Eternity. When doing turn based in those games, it takes too long due to combats being everywhere and "trash" fights that are ment to take 10 seconds end up taking 5+ minutes.
BG3 is like the DOS games, made for turn based and combat designed as such. So, most likely will feature the same as the DOS games, every fight is handcrafted with no random encounters.
BG3 could end up as my all time favorite RPG if they manage to add inn the BG story and overall grand arc of it along with the darker tones + add in the hand crafted turn based combat. I tried BG 3 when it first launched 3 years ago, and it was way too much like a DOS 3. Too bright, bloom everywhere, and didn't feel like BG at all. They've since toned that way down and it looks much better. Combat though, while even better now, is great.
As to liking it, most likely. Combat is designed from a game you love, only more tactical, and story will most likely be much better. Reason I say most likely and not a guarantee is that I don't know how you feel about
a lot of talking and story. You spend quite a bit of time talking to people (and animals), and skipping it might be an issue since majority of chats include dice rolls (easily expect 3-4 dice rolls in one chat) which impact resulting story, fights, events and whatnot. And while you can savescum chats to get a result you might want, if you fail on the 4th dice roll, you have to roll each of them again and get all 4 in a row.
Already early on in Act 1 I encountered talks where I went "Wait, what? How did..." only to try later and figure out I had missed some talks who explained things or added chat options. And they said in the panel now they've added 33% more to react to even more things. You talk to random npc04 kid running around which suddenly might give hints to a quest that lead to an area which starts a fight which triggers X, Y, Z event and if you didn't talk to NPC02 kid people die, but talking to an animal before then stops it and rather starts another quest. That's small village stuff. Baldurs Gate is going to be .... I think that might be the "bad" for many. Talking is an actual mechanic of the game.
Edit: Note about talking though. Voice acting is superb.