Surprisingly Improved Sequel: High Impact Games took advantage of the PSP's additional processing power this time around. The levels are bigger, and more detailed. The number of enemies and NPC's on screen is higher and the sound effects are more impressive. Though it's still seen as Sequelitis for fans of the Insomniac titles, and the main consensus of the game is that it's So Bad, It's Good.
They Wasted a Perfectly Good Character: The Thugs-4-Less leader from Going Commando appears at one point in Ratchet's prison, leading other imprisoned thugs to take revenge on Ratchet. You'd think he'd become Ratchet's antagonist for the rest of the game, but he abruptly disappears after one cutscene, and doesn't even appear in the gameplay after that point.
That One Boss: Klunk is ridiculously difficult in challenge mode; his attacks can kill Clank in just a few hits, and is so durable that you'll be running out of ammo before the halfway point.