I'm on the verge of buying one for this, Noby Noby Boy, and Echochrome, which I'm fairly sure makes me a full-blown retard. Sure, I'll end up picking up other games, especially if Fumito Ueda gets off his ass and releases something this hardware generation, but really, it's all about those three for me at the moment.
I've only played it a little bit at a friend's but that was basically how I felt as well. It reminded me of Donkey Kong Country. That is, really nice platformer, but just a little more linear than I like them to be.
I can already feel the sadness this game would produce by sucking months and years out of someone. Maybe it would also instill a faint hope that they could possibly, somehow, become a game designer by making things in Little Big Planet. Yes, it would lie to them. Whisper to them sweetly and consume their souls.
I fucking played the shit out of Contra, and I would play the everloving shit out of this. I was rockin' out to the Dragonforce-esque theme, too. Better than most of the LBP vids I've seen.