Good Toy, Bad instrument.
Black keys don't work. The touch keys are reactive, but not reliable enough. On the one we have we often have to tap a note twice to obtain a sound. Also the last b key sometimes fires on its own for no reason. That's enough to make it unplayable as an instrument.
As for build quality, it's ok. It has endured four years with a (quiet) kid.
There's a nice setting/mode showing colors above the 'correct' key, waiting for the child to play it back to go to the next and then playing the entire song back at the end.
Unfortunately there's also another mode, assigning random funny noises (animal noises, horns, cartoonish sounds,...) to the keys, allowing the kid to make maximum noise while an unrelated playback is playing above it all.
Guess which mode is the kid's favourite ?
Good toy I guess. I hoped for something a bit more educational when I bought this from an online instrument reseller but I should have been more careful.
If you want your kid to think all real keyboards are lame because they don't have colors and funny sounds, it's a perfect buy.