I've just been doing a little research into this game (which will be available on XBLA soon, or possibly now in some places) it sounds very interesting, as well as being creepy as hell. As far as can tell the only story aside from hints within game is in the games description, which says that "a boy worried for his sister enters Limbo." The gameplay itself revolves around punishing platforming and puzzles segments with nasty consequences for the young protagonist if things go wrong.
While I was very interested gametrailers review said that the game is only 3 hours long. As 1200MS points (I think) that's pretty steep. I was just interested to see if anyone else is thinking of getting this game, or if it's already out somewhere (I should probably do my research before I do these things) whether anyone has bought it and thinks it was worth the price.