My first thought when seeing the graphics of Back in Action was that it looked only slightly better than that of the PSOne, but after a while the level of detail present in the game began to come out and I started to realize that the graphics are more complete and better than I originally saw. The cinematics are a mix of in-game and fully CG movies, and the only time the character models appear to have too few polygons was during the in-game cut scenes. Besides that, the camera is positioned just far enough away to give the appearance of nice and smooth character model. As far as the pre-rendered movies are concerned, those were outstanding. The level of detail and effort (not to mention time) put into these movies is impressive on its own.
The music of the game has a very lighthearted and happy-go-lucky feel to it. But the best part of the music is that they are still tailored to the location. The voices used are straight from the cartoons and give the game a great feel. The game does have a flaw in the sound department. The characters tend to talk a little too much, which means they will run through their list of comments rather quickly. Thankfully the number of statements they make isn't as small as other games.