Ratchet: Deadlocked is a fun stand alone game, but in comparison to the rest of the series, it falls flat on its face.
The box art alone should tell you something. Ratchet is no longer the lovable chartacter that we knew all along. This game is just the latest in a trend to make videogame characters darker. The level designs are no longer colorful and fun. Rather, they are all dark and seem to blend together. A lot of the humor in the series is gone. In place of funny announcements over the intercom systems on different planets, you are left with half funny commentary by the two announcers who accompany you the entire game long. Clank barely makes a cameo in the game, as well as everyone else from the Ratchet and Clank universe except for Al, whose sole purpose is to fix and upgrade your two robot guides, which fight with you at all times. This game seems very untied to all the others. This isn't necessarily a bad thing, but it doesn't work well in this instance.
The game does have a few saving graces, but in comparison to the marvelous series before it, this game falls flat on its face. The online multiplayer is pretty good for Deadlocked, which adds a lot of replayability to the game. For all the shortcomings in the single player mode, the online multiplayer seems to make up for them at least partially. Also, the game brings new difficulty levels to the table, adding a challenge to the single player mode that really wasn't there in previous games. My younger brother was finally able to beat a Ratchet game when he put the game on the easiest of difficulties. Overall, the Ratcht and Clank series is great. However, with Ratchet: Deadlocked, you are better off passing if you don't have a network enabled PS2.