It's a great Magic: The Gathering game and most important, it's free!
I downloaded it from the Magic page and installed it, it took some time to actualize. I really liked it, even though the graphics or the sound aren't so good, the possibility to play with other people makes it a great game. Beside it's easy to use...
The only bad thing: it has to actualize every time you run it, and depending on your Internet connection velocity and the time you haven't played it could take a while