Play the entire series, it was my first shooter, AND IT WAS AWESOME. I still have all 3 for the PS2 and the Deadlocked thing (still fun, but it was a completely different thing so I don't count it), and it's now the #1 reason that I'm jealous of you bastards with PS3's
As for games like it, the original Jak and Daxter and the Destroy All Humans games come to mind, but not much else.
edit: I don't give a shit if you don't have a PS2, go out and get one. There are so many awesome games for that, that I laugh in the face and piss on the home of someone who doesn't own one or one of the backwards compatible PS3.
edit 2: ^Listen to that man. They're very different games, but you can see Banjo and Kazooie influenced a great deal of Ratchet and Clank's platforming sections. They basically invented the idea of controlling 2 characters who work in tandem.