I give it this feedback in regard with the overall playability. Don't get me wrong, I knew what I will get for the money.
The worst thing, are the keys - you don't have any feedback, are very light and if you force it sideways, it can be overlapped with another key.
If you want to learn to play piano/keys, don't buy it. I'm using it for pads (nothing more), in tandem with another piano so it's for this, is ok.
The signal delay is acceptable, there is no lag. The sensibility of the key is on 5 or 8 levels (not from the books, from what I've experienced), so not that great.
Overall, is cheap instrument, don't expect anything special.