I reckon the stat inflation which moves exponentially as you level up is a major problem in the game. Regarding design, I find the game doesn't flow like an rpg should. You are kinda forced to do a bit here and then a bit over there, which in role playing terms is terrible. It's a game where using a walkthrough helps way to much, and not using one is painful.
Mainly because while it makes sense to finish the lower level areas first, in each level the boss fights can be really difficult, almost impossible without coming back later, which does nothing for the role playing aspect.
The ridiculous stat inflation is largely to blame. In the first act you can safely take on opponents who are a level or two higher than you. As you progress in the game that becomes more and more difficult. Consequently, a boss who is just one level higher than you becomes virtually impossible unless you cheese.
Regarding the bugs, while there are way too many, they also need to work on balance in order to make combat more enjoyable.
