Ratchet and Clank come back stronger than ever. Read this review if you want the real story.
Weapons can be leveled up to level 5 and then more in challenge mode like before, but now there is a way to customize the weapons. Each weapon has a grid and you use rareitanium to upgrade it. The whole thing is hard to explain, but it is a great feature.
The other problem that gamespot has is the difficulty. It is easy, but when was a Ratchet and Clank game actually hard (and it does get harder towards the end). Difficulty is just not what you buy these games for.
The only reason I don't give this game a 10 is because of the camera. There are some points in the game where you don't have as much control of the it as you'd like but it really isn't that big of a deal.
The graphics are amazing, the game uses great use of the SIXAXIS controls, the weapons are better than ever, the clank levels are outstanding and a lot of fun (you can even slow down time when you clank!!), the story is great (in my opinion at least), there are more planets, more unlockables, and all around more fun than in the previous games. If you liked the other games, getting this one is a no-brainer. And if you haven't played the previous games, you will still understand the story as much as any of us.
BUY THIS GAME!!!!!!!!!!!!!!!