It would be best for you to play Divine Divinity to get an idea what to expect. This game will be very similar. It is also really cheap to buy now and last year it was 'regraded' by a video game magazine that got an ~80% in comparison to the latest gaming technology. Not bad for for an old game.
The game will be big, but will be full. Every area will give you the feeling there is a purpose for this. Expect no wasted space or 'sloppy filler'!
I did play Divine Divinity LightnightLocky and Beyond, And Ego Dragonis, and trust me the world of Ancaria is huge in comparison to Rivelon, but i did enjoy Rivelon so i cant wait to see what secrets they will have for us in this one