How is the actual playing experience? My expectation is that it feels a lot like DOS1/2 in terms of movement and action distribution, and that it's going to lack a lot of system refinements that would have come with a system built for TB from the start. But I'm curious re. any Codexers that have actually played it for a few hours.
It's ... slow. I'm partway jaded, because I don't enjoy any of the non-combat elements of this game, whilst turn-based is at least making combat more fun. So far. The initial island experience has been a taste-test of what I suspect the later, more 'challenging' fights are going to be; HP bloats that are exaggerated by massively variant RNG (d100 is horrid) that I swear is wonky - I've missed more 90%+ attacks than I've landed. Bizarrely, 60-70% hit-chance seems to be where battles go steeply in my favour.
If you enjoy Pillars' writing, I think this is most definitely a step up. If you don't, then I think the game is just going to feel far too slow all around to be possibly enjoyable. I've only finished the first island, and even though I was enjoying the later fights (again; take the skip-to-four blessing; I went without and it's a chore), I'm kind of sitting around not overly eager to play more, because I know of what I have to trudge through to get more combat. I'm not sure if the turn-based is good, but it's satisfactory. DoS1/2 do it far, far, far better - even 2, whilst bloated by the silly armour system, carried more impact with every action made.
So yeah. Like the writing / base game? Dive in.
Don't? At least try the first island to see if you enjoy playing around with the abilities with the level four skip. I think by time you're ready to leave Maje, you'll have a solid idea of whether the rest is worth playing out or not.
Edit: Oh. As for the actual play-out? It's Movement + 1AP. Some actions (typically self-buffs or dashes) are free, others are either used immediately (Standard) or later in the turn order (Cast), each costing the 1AP. Movement is very generous, but also broken by abhorrent path-finding. Your turns feel a lot more claustrophobic than in Divinity due to such limited actions, but on the upside, you can plan out combat and arrange tactics considerably more easily than in RTwP - spells and abilities are much less of a chore to use.