I give 4 out of 5. One point missing because:
1. No multi-player! What the cluck is up with that? This would be such an awesome multi-player game. I'm a big Magic: The Gathering fan and this is about as good of a mimic as you'll find. I can't stress it enough, IT NEEDS MULTI-PLAYER! It would easily get a 5 stars with MP.
2. Too few challenges/missions. They really fly by when you get into it and leaves you wanting to keep facing new enemies and challenges.
It'd be awesome to be able to use a customize deck for the AI. It would be great for practicing and creating those challenges for yourself. And do away with some of the animations, such as the arrows. Using still images is fine, it's not something that needs to be dressed up any.
Other than that, great game. Very satisfied battle card-game fan.