Many reviews of this film make the criticism that it reads like a series of cut scenes from a video game stitched together, but I don't see it. There are plenty of character moments, quiet stretches and world building that the Ratchet & Clank games tend to do in voice-over during gameplay. Being a film aimed squarely at children, there are a couple of recurring jokes that grate, like Blarg playing with phones and Ratchet's boss being unable to operate a cherry picker, but the characters are fun to be around and many of the elements that made the game so good translate across media perfectly well. It's a lot of fun to see the Sheepinator, Buzz Blades and Swingshot on the screen, and whilst the RYNO not being used at all feels like a misstep, its showing up is a fun sequence anyway.
This is far from perfect, but it's enjoyable enough and worth a watch if you're a fan of the games. It doesn't quite capture the charm and genius of the games, especially the PS2 trilogy (before they got overly pretentious) and the sequel tease will never be realised, but there's enough to enjoy. I picked this up on DVD from a bargain bin, but if you can stream it, that may be the better way to go. What you're probably better off doing is picking up the Ratchet & Clank Trilogy on PS3 or from PSN if you can, they're fun games and the third in the series may well be great. Classic characters, I'm hoping this isn't the last time we'll see them.