You'll spend a lot of time with this game...
a) You like it a lot
b) You're so frustrated you want to rip the game out of the console and film yourself cutting it into pieces and then posting the video on Youtube
c) You just returned it after playing it for the first time.
This game definitely has a lot of good things going for it and a lot of bad things going against it...
The Good
You'll get your money's worth if you don't throw your controller at the screen, the game will take hours and hours and hours. A single round can last over an hour. The story line is pretty original and the game play is like a card-game/board game. I don't want to spoil the story, but the gameplay isn't too hard to learn, but if you're going to pass the 4th level, you're going to have to know more than your basic cards. I'd suggest editing your deck before every level (you can have 50 cards) mixing your deck with the appropriate amount of creatures, spells and items.
The Bad
Each game is quite long. The first round took me over an hour and my first achievement of 5 points was about 3 hours of playing the game. The game does get slightly easier in which you learn the intricacies of each creature, spell, item, support, etc., but sometimes you will feel like the computer is cheating!
If you like puzzle games, and you don't like to lose and you want to spend a lot of time playing a game... this is the game for you...
Best of luck.