The game is definately a low-end Diablo-style game. But then, for a $15 price-point, I would NOT expect a high end game (with a notable exception of Van Helsing!). As other reviewers stated, there are lots of minor bugs and the voice acting is so flat that it is terrible.
When it works, the game can be fun and there does appear to be a good story in the background. The main problem was that there were times when a dialog box was supposed to appear and you are supposed to be shown some text from the story but when that dialog box didnot appear, the game was stuck. You couldn't do anything except CRTL-ALT-DEL to quit the game. That bug has since been fixed in a recent update.
User interface: 6/10
Graphics: 6/10 (too dark for my tastes)
Sound: 5/10 (music is repetitive)
Voice acting: 3/10
Stability: 9/10 (the game never crashed, but it did lock up numerous times before a recent fix; havent played since)
English: 6/10 (numerous small English mistakes. Some actully seem to add atmosphere, though; e.g., Conan the Barbarian)