Personally, as someone who hasn't played the game, I enjoyed it. From what I understand, the game is way more amazing, but this anime, from my standpoint at least, was pretty awesome.
I like the way the classroom trials were set up. It was interesting, and I haven't seen anything like that in an anime before. I also think it was fun to try to solve the mysteries as the story progressed.
Admittedly, the plot didn't seem to be paced very well, but other than that, I don't have any real complaints.