This game is FREE on PSN right now, and well worth it for $10 now that I've played it with friends and had fun doing so
This game is great fun to try and get Gold on the challenges and unlock trophies. Some crazy people will try and get the highest level, Plastic, which unlocks the Sackboy costume, that's just crazy to me as gold was hard enough.
What isn't so good? Well this very polished game lacks in content. There are 9 stages, 4 game modes (all of which are fun however), and about 10 challenges. That's it. You can play with up to 4 players locally but missing online multiplayer hurts it a lot.
If they spent a little bit more time on this game adding a few more challenge modes and stages it would be nice, but mainly online multiplayer it would be amazing. But right now its FREE, so go get it, grab some friends, and have a blast just like playing Smash Bros.