tldr: This is a great game if you enjoy rich storytelling, compelling character arcs, and actual consequences. This is also a great game if you enjoy turn-based, environment-aware combat of the likes of Fire Emblem or Final Fantasy Tactics. Overall, it's a well-oiled machine, with polish in all the right places to make it very welcoming to dnd newcomers and veterans alike. If you have played Larian's older Divinity: Original Sin games (which was not based on the dnd ruleset), there's a lot of quality of life updates that fix a lot of the gripes that I had with those games.
My wife and I are loving it (individual saves, although co-op is supported in this game). We are not dnd tabletop players; the extent of my experience is the recent dnd movie that came out. I don't know the difference between 5e and 3e, but I do know I'm having an (eldritch) blast playing this game. I bought it on a strong recommendation from my friends (although, these friends do have dnd experience), and I can confidently say it's a fun game.
The most overwhelming experience you might have as a newcomer is during character creation, where a healthy amount of reading is involved to understand what classes, races, subraces, spells, and cantrips are (among other things). They provide very neat tooltips that provide the information you need, when you need it, without getting in your way - there is no pause-every-5-seconds-for-a-tutorial-notification deal here. You can get involved as much (or as little) as you wish. If you've ever made a character in a game like Cyberpunk 2077, Star Wars Knights of the Old Republic, or Dragon Age: Origins, and messed around with the relevant skill trees, it's around that level of involved.
If you do get overwhelmed with character creators, fret not - you can choose one of the pre-built characters that come packaged with their own personalities, builds, and stories. Speaking of stories: I personally feel like the writing is compelling and is leagues better than previous Larian titles, if that means anything to you. Make no mistake, this is a fantasy story and you'll have your fantasy tropes in this game, but I've yet to encounter a moment or twist in the story that feels cheap or unearned. It depends on how much you like this sort of genre. There are times when it takes itself seriously and times when it doesn't, but it has never felt out of place.
Besides the narrative, the other major part of the game is combat, and I think it shines there too. From a non-dnd perspective, it's a turn-based, environment-aware tactics game. It doesn't feel exactly like any one type of system I've played before, but I feel a lot of different aspects that get utilized in ways that mesh well. Unit placement on the field matters. Typically your party's makeup plays a role in how you approach encounters. I've never felt like my party couldn't figure out their own way to solve a situation, and it never felt like it was just handed to me. The encounters are flexible enough to allow multiple approaches without depriving them of the depth each approach needs to remain engaging.
Just so you can gauge how well my suggestions will apply, I love playing tactics games but don't always have a lot of time, so I typically adjust the difficulty when possible to emphasize story progression over tactical difficulty. I'm not a maddening-difficulty Fire Emblem: Three Houses player (more power to y'all out there); I just casually enjoy combat puzzles. I think games like Fire Emblem: Three Houses, Final Fantasy Tactics, Advance Wars, Tactics Ogre, Brigadine, Battle for Wesnoth, etc., are fun to play, and I don't necessarily need to "win" every combat encounter to feel like I had a good time either. I really enjoy is a story that presents fresh ideas, even if it means remixing some old tropes here and there; Star Wars: Knights of the Old Republic, Dragon Age: Origins, etc. - any game that gives you characters who mesh well (or "contrast" well) with one another usually can maintain my attention.
As @bigevildan said, they'll all be recruitable. There is also the option to play as an amnesiac custom character that gets their own origin background. No spoilers as to what that is like, but it's a possible option if you're not quite sure. (I've seen it recommended to avoid that for your first playthrough, however).