Got very good reviews... but I've never figured out what the actual game is?
So... can someone explain in a couple of sentences? Also, is it fun to play offline? I'm not into online gaming, so I need to know if this is a good solo adventure?

cheers,

-avatar!

LBP is basically a 2D platformer where the player is given free reign to edit level content, apparently. Downloadable content includes (but is not limited to) character skins and player-created levels.

By edit levels you mean make your own? Is it a long/good solo game experience?
Does it also have a story/plot with an intro, ending, and all that jazz?

The game has an okay single-player mode. I didn't get far in it just because I found the platforming to be mindnumbingly boring.

The main draw of the game is in the user-created levels (and in creating them yourself). But as expected, the quality of those levels is very hit and miss.