Very immersive, I loved it!
I played a DEX archer, with long range shoot (1st DEX) + knockback (2nd DEX) + regeneration (1st misc) + heroic aura (4th misc). It felt too OP sometimes (the boss was nearly an insta kill).
The mixed, free ability tree is awesome. I really liked the idea of having swords that have INT, allowing some sort of warrior mage. However, since I'm not very good at RPG, I was getting worried of not having more DEX skills and having to start to think about what's next. Luckily, the demo ended, leaving a very sad feeling (good job!).
Finally, I felt that the STR and DEX stats were too similar. It looked like I could just go and acquire all the STR abilities after the DEX tree without any penalization on my bow damage. Maybe that is intended, given the free nature of the ability tree, but introducing some opportunity cost would build another layer of decision making (should i keep increasing DEX even if I have access to all its abilities or go with STR?).
I'll purchase the full game, thanks!