Really nice
It took me 2h to complete it and it was great. 50 nights = 50 deaths.
What I didn't like:
Pausing the game while a boss fight can easily kill yourself, maybe use a little countdown, just as in Guitar Hero.
Sometimes my mouse was stuck and I got killed, but I think that was due to freeze.
The leveling could be a bit faster, maybe 5% more exp./enemy, since I don't want to play this game again.
In the beginning I spent all my crystals into the beast and bought lifepotions only before the last level.
These were still minor things.
The graphics weren't that great in my mind, but the figures itself, in the first line the beasts were really well designed.
Oh yeah, the story:
boring.
confusing.
more like: power rangers with dragons and an emporer but wtf! :)