So I was one of those geeks/nerds who played magic back in middle school and spent way too much money on it. Was good times though so was excited when I heard this was coming out on XBL. Downloaded it last night for 800 points I think it was.
I'm pretty impressed with the actual game play with how/when cards are allowed to be played and it gives you a short chance after each card is played in case you are able to counter/enchant/whatever. Overall it's a smoother experience than what I expected.
The only problem I have with it thus far is the inability to really customize your deck. You start out with a basic green deck and unlock other decks as you beat various computer players. There looks like 8 decks you can unlock, 1 of each color then a couple combination decks I imagine. Also each deck has a set of 17 or so cards you can unlock as you do more things in game. I'm not sure if there's an actual place where you can see all available cards in the game, but it doesn't seem like it. I just hope as time goes on they'll add more DLC card packs or something since one of the more fun aspects of the real card game was collecting the rares and building your deck in different ways.
There's a single player campaign mode where you just battle one on one with various cpu players. There's also a puzzle mode where you join games already in progress and have to accomplish a set goal like "given these cards in this situation, defeat your opponent this turn". You can challenge other people via XBL and there's even co-op modes to fight the computer or possibly 2 vs 2 via XBL.
There's a bit of a learning curve I think when you first start playing and having previous knowledge of the game helps greatly. They do have a full fledged tutorial to teach you everything, but if you're coming into the game cold it can take you awhile to catch on I think. Once you understand what's going on though, it pretty cool.