It's... okay. As a standalone game, it's fine, but compared to the series, it's disappointing. Even with custom servers online play is impossible, not to mention the harassment of loading screens. I hope they make Littlebigplanet 4, but who knows.
It's a cute game, sort of like a watered down version of the first littlebigplanet. It isn't to be taken too seriously as a game, but it's still really good nonetheless. Downloading levels and online play can be finicky, but for the time it's great!