An indescribable amount of contraptions can be created in LittleBigPlanet, and implemented into an indescribable amount of indescribably unique and variable environments in an indescribable number of ways. What I'm saying is, LittleBigPlanet is almost limitless.
Of course, it isn't literally limitless. No game could possibly be limitless. You'll probably hear a lot of people claiming that LittleBigPlanet's only limitation is your own imagination or some shit, but that's just retarded. It goes without saying that you can do a lot in this game, but you'll probably get bored after a little while because you'll be sick and tired of playing endless levels involving roller coasters or some variation thereof.
When playing through the many already available levels created by other players of the beta, I noticed that many of them were either rip offs of similar levels or were very unimaginative platformers. However, I also found a handful of incredibly unique and original creations that were truly fun to play. I saw Rube Goldberg devices, primitive yet clever machines that could walk on their own once activated by a switch, imaginative levels that actually require thought to complete. I even found a level in which you hop onto a relatively slow-moving rocket-propelled car that triggers a series of audio-emitting devices that play Sweet Child O' Mine note by note as you proceed.
Thankfully the game has a level rating system, so I'm sincerely hoping that occasional gems such as these will quickly rise to the top, while the never-ending stream of poorly designed and ill-thought-out levels remain unseen. Yes, there will be a never-ending stream of ill-thought-out and poorly designed levels. People are stupid. Get used to it.
In terms of the game's controls, visuals and playability, it's definitely above average. Using the tools is very easy and straightforward, and the tutorials help you to quickly understand the game's capabilities and learn how to use the tools. It's not always perfect, but it's definitely not bad. Controlling the Sackboy can be a little more difficult. The jumping doesn't always work exactly how you'd expect it to, and since the platformer-style levels have a few levels of depth (which significantly adds to the cleverness of some well-made levels) the Sackboy can often move back and forth between these levels even when you didn't want him to, often at the exact moment that you really don't want him to deviate from his path, because it's surrounded with electric spikes. It takes some getting used to, but it's not too bad.
The game looks pretty good - although it's not as good as the trailers and other such promotional material would suggest, it's still a treat for the eyes.
In summary, LBP will be a lot of fun, probably for quite some time, but like all games, it will get boring eventually.