How does this compare with Divinity II? Have bought older versions of games I've enjoyed and am always disappointed. Is this worth a go?
It's not horrible, but it is most definitely unpolished.
There were a lot of very questionable design decisions, particularly about the overdesigned skill and resistance systems.
The skill system is obnoxiously over-specialized, and you get far too few skill points at the lower three difficulties than you need to specialize even a little. Magic is horribly nerfed in the game, it costs an insane amount of mana for little damage. You'd need to spend a lot of stat points on Intelligence just to get enough for one or two additional casts of a useful spell.
There is a large complicated Resistance system with 8 possible resistances, and it's worthless because after Act 1 most enemies resistances are around only +/- 10 to everything anyway.
There's a lot less to do in this game than in DD, both because the game is shorter, and because there are numerically very few side-quests. In some places you need to side-quest to advance the plot, which means is that you need to do most of the available side-quests. That doesn't help with replay value.
There are some good things though, the summoning dolls are essentially a portable, infinite-storage chest you can bring up at any time, one you find a Battlefields key in each act, you can visit a merchant at any time for repair, identification and selling stuff.