This has probably already been said...but I'll reiterate:
If you are in any way a platform fan you need this game. I say that as someone who dominated SMB 2 Japan SNES All-Stars version (got A-B-C-D and Level 9 opened and completed) and got 100% on every Yoshi's Island stage.
This game is balls out platforming greatness, I can tell after just the first 'world.' I can only imagine what lies in store for me.
Two things really take it to platforming bliss and make it something all new:
1st. Levels start out really small but just expand, but the music doesn't start over every level or every time you die. Instead it just keeps going, building and growing. And when you die there's no useless screen or anything, nope it just throws you right back in there like an FPS or something.
2nd, and most important. It makes you appreciate your 'stupid' deaths. In platformers back to the original Super Mario Bros, we've laughed at our friends as they gear up to make this awesome jump only to just run off the cliff harmlessly. It's hilarious, and when it happens to the gamer it's infuriating!
Well Super Meat Boy as we all know records all your deaths and then plays them back on top of each other. I did not anticipate how great that would be. Not only graphically while you are playing the world, seeing all your mistakes in blood all in front of you. But the replay, you can have a good laugh at the time you jumped right into the saw right off the bat. Or you can cringe at how you f'ed up right at the end, as two Meat Boys fight for the princess, with only one to make it!
The sense of humor is right up my alley too.
Fantastic game, could end up being my favorite XBLA game to date (although admittedly that isn't saying a lot.) If it does though, it would be a surprise to me personally as Bionic Commando was one of my top 5 NES games growing up. To put Super Meat Boy in that class already is as high an honor I can give it.
Can't wait to see what's next (when my hands stop cramping!)