This is one of the most fun games I've played on the Wii. It has style, wit and gleeful anarchy in play (and even more so in the story that frames it).
So. Play. You are a round blob with a funny expression, and you can soak up paint and then paint things by bouncing against them. The controls are fairly simple - nunchuk stick to guide you, flick the remote to jump, Z to target things (paintbots, bad guys, buttons, etc) to jump on them. It's basically a platform game, with the added bonus of letting you splatter paint over a blank city however you like. Each level is huge (taking an hour or so to complete) and there are a bunch of challenges - little timed tasks - that give you extra points. Some of these also stop bad guys spawning, or get rid of dangerous black ink. All good, with the exception of jumping from building to building, which is supposed to be useful and give you bonus points, except instead it is utterly random where you end up.
This is all wrapped in a glorious piece of utterly mad story. The facistic inkies have taken over the city, removing all the colour via paintbot and trapped all the inhabitants in gray suits. You are a jungle dwelling blob, recruited by the colour resistance (a few other blobby characters) to strike back. The cutscenes that start each level, and some of the story-related tasks in game, are hilarious. Best quote: "They have forced all the musicians to become accountants!" The craziness is included everywhere - the way that major buildings get redesigned when you take them back, the patterns that you can pick up to make your painting more varied, the musical stings that play when you paint something, and so on.
The multiplayer modes seem quite fun too, although so far I have only played them with my daughter, so I'm not sure how they will work when ruthless competition is active. There's no reason they wouldn't be - the competitive painting one at least was pretty neat. Also, on the topic of kid-friendliness, once you have completed a level, it can be opened in 'free paint' mode, lacking all enemies and objectives. This is a bit hit with her.