It's a very good game. The complaints about its camera are overstated - the style of camera it uses employs automated splines to swing the camera to certain positions in areas to give a specific view in an attempt at clarity; rather than just following Mickey from behind his back. There are moments when the camera goes too far or lags behind, but it's really not bad.
Also, I am not sure I'd agree it's "for kids". The tone of the story is actually rather neutral and has some good humor to it. The in-game story scenes are actually some very nice, highly stylized 2D animation that doesn't pander to kids with an overly cute presentation. It harks back to classic animation styles such as Max Flescher's work. There /are/ probably a few too many tutorial reminders early on and the beginning of the game is slow. However it is a very long game with a lot of content. There is a whole lot of game to go once the training wheels are off.
The visuals are some of the best stuff on the Wii hands down. Some folks are real let down that it doesn't use the dark steampunk style of early concept art. But there are many areas and several styles of art. Some areas are dark and gritty, and some are creepy and dilapidated. It runs at 30 frames per second and there's a bit of stutter here and there, but it never really slows down much or for more than a second. There are a lot of lighting and visual effects, and very nice painted-art style shaders on Mickey and other characters.
The character animation is very high grade. Rubbery, fluid, cinematic. What makes the whole game a lot of fun is that they nailed movement on Mickey; he is super smooth, responsive, especially his jumping and double jumping. His animations give him an excellent sense of weight and reaction to the environment. The painting effect is very nice and fluid and gloppy.
There are more platforming sequences than it may look like from some screen shots, and the paint mechanic is worked into many of them. Early on for example, you've got to deal with freezing rotating platforms by dissolving their gears or by restoring them at the right time. The painting and dissolving concept is simple, but it gives a feeling that you are doing things to the game world rather than merely wandering through it. It feels like Mickey's actions matter.
The story to the game is really very good, but more to the point, it's intriguing. The whole business with Oswald the Rabbit, the lost Disney character, is handled with surprising depth further into the game and it is clear Oswald is a co-star with equal weight to Mickey.
The decision-making concept in the game factors more into replayability and variety more than dramatically huge differences in the plot. A nice touch IMHO is that the many (MANY) quests you can take on for characters in the game world can be failed permanently; in my view, this encourages replay down through the months or years, to try and make that "perfect game" where you don't let anyone down.
Finally, the composition of the music is very high quality and makes excellent use of the Disney library of musical cues the developers were given access too.
For my money, it's one of the richest games on the Wii; it is not an innovative platforming tour-de-force like Super Mario Galaxy. It relies on older, bread and butter concepts that remain solid but are executed with some depth. It comes across to me as a comfort food game; not particularly innovative in most areas, but executed at a high level of quality and having no rough edges. It's also a style of platformer that we ironically haven't seen a lot of in recent years. It reminds me of games like Banjo Kazooie on the N64 (just a lot better) or Rayman 2 on the Dreamcast, if anyone remembers that.