If you're bored with the usual run around and kill gameplay, you should definitely try a Katamari game!
Anyways.
This is your average run-of-the-mill Prince of the Cosmos has to roll up everything in the world into a giant ball so the King of the Cosmos can make it into a new star... game. Which is to say, it's completely different from every other game out there (that isn't part of the Katamari franchise, natch). This is the only Katamari game I've played, and while I enjoyed it, I doubt I'll seek out the other games in the series, as I don't know if I want more and more of the same fairly repetitive, albeit innovative, game mechanic.
Each level in the game gives you a slightly different world and usually a different task. In one level, you have to create a giant snowball in a ski resort to put on top of a giant snowman, by rolling up everything in sight (people, sleds, even campfires). In another level, you have to make a giant sumo wrestler by rolling a skinny guy over food in a crowded marketplace. In what is probably the best level, you just have to make the biggest katamari you possibly can, starting out on a normal street rolling up trash and debris and eventually rolling up everything from Godzilla to the Taj Mahal to even the faces on Mount Rushmore.
And many more (roll up all the continents, roll up all the sweets, roll up all the paper cranes, roll up all the flowers, roll up all the clouds, roll up all the fireflies, etc)!
As fun as this can be, it can also get tiresome after a while, and I was done with the game in about two weeks. Also, the load times. Maybe I had a flawed copy, but load times stretched in two solid minutes for me sometimes, causing me to have a game of Hexic loaded up on my 360 to switch over to whenever I started a new Katamari level just to stop me from pulling my hair out.
In conclusion, if you're bored with the usual run around and kill gameplay, or you just enjoy quirky miscellany, then you should definitely take a Katamari game for a spin around (or over) the block.