Ratchet & Clank: Going Commando was almost perfect. Insomniac found the perfect balance of shooting, platforming, exploration, and change-of-pace minigames. A weak final boss and an absolutely godawful turret-based boss fight mar it slightly, but Going Commando is about as close to perfect as a game can be.
Up Your Arsenal improves upon the shooting, at the expense of the platforming and exploration. Next year's
Ratchet: Deadlocked would do the "all shooting" Ratchet game better than UYA, leaving this game as a bit of an awkward stepping-stone between the franchise's two best games.
The main problem with Up Your Arsenal, however, is in its change-of-pace minigames that break up the shooting, which drag on far too long and absolutely cripple the game's pace. The first of these is the 2D side-scrolling levels where you play as Captain Qwark. Despite some excellent framing cutscenes, these levels are a mediocre-at-best experience, and there are five of them sprinkled throughout the game. God help you if you mistakenly think the second and third are optional because of how nonchalantly the game throws them at you, because then you'll be stuck playing three in a row at a key point in the game's narrative.
These levels are very forgivable, however, in comparison to the true backbreaker for this game: the hacker. Up Your Arsenal loves to throw hacker puzzles at you in the middle of levels. Not just one per level, but usually three or four in the levels that feature them. The hacker puzzles take up what feels like ages as you monotonously spin a barrel to shoot red pieces and pick up green ones. And then you learn that these puzzles can and will have multiple layers. The late game features four-layer hacker puzzles that absolutely tank the levels' pace. You're having fun, then BAM you'd rather be doing your taxes. More often than not, I stop playing this game after its first act due to the introduction of the hacker.
When this game is hot, it's on fire. So much, in fact, that Insomniac calls the fire department to spray you down with a high-pressure hose of monotony.