The Fisher Price "I Can Play Piano" is the modern successor to the old Miracle Piano Learning System (which used to be available for your computer or Nintendo Entertainment System). It comes with an AC adaptor, and plugs into your TV with an attached (and not removable) set of RCA cables. You can play just the keyboard without a TV, but the sound is limited and there are no special features when you play without a TV.
So how does it work? There are just a few modes, and our 5 and 3 year olds can set it up quite easily. There's a game mode for learning the keys, a song mode for playing along, and a freestyle mode for just banging on the keys, haha.
But does it really work-- does it teach the kids to play piano? Sadly, no. I had hoped the keys would light up, as some do. Instead, they are color-coded, and you press the appropriate color when prompted by the game or song. The problem here is that the kids have to move their eyes from keys to screen, quite rapidly, even on the easiest settings. This really only encourages them to slap at all the keys, in hopes that they'll score points.
So you'd have to stay on them pretty closely for this to do any good. It isn't bad, but it won't make them into a concert pianist overnight either.
Bigger review with screenshots coming soon!