Short summary:
The pedal is very cheap, and surprisingly good considering. I can easily recommend it to just about anyone who wants a good pedal cheaply. The only issue I had with mine is that it is slightly prone to slipping.
Long review.
I bought this pedal to use with my NP-32 Piaggero, as I needed a cheap pedal that I didn't have to worry too much about breaking, all while refusing to use one of those plastic lumps that you periodically get whenever you buy a keyboard.
The build quality is fair, the pedal feels sturdy and able to withstand a beating, but it's also light and easy to bring with. The only thing that really lowers the score, is that it is a little bit prone to slipping.
The polarity switch is a big plus. Sometimes, I teach small children, who presses the pedal before the keyboard has had an opportunity to start up, or accidentally pull the pedal cord out while playing. Without the polarity switch, one has to restart the whole keyboard in order to fix the error, but this is not necessary with this pedal, due to the polarity switch. Also some Casio and Akai keyboards have inverted polarity by default; which is a big issue unless you have their specific reversed pedals.
Another big plus is the feel. It is quite similar to a real upright piano pedal if you don't look at it. Quite clearly it is not quite the same, but for the very low price, it is certainly worth it.
Unfortunately it does slip around a little while playing, as mentioned earlier, This, however, can easily be countered by putting some anti slip material or tape underneath it.
To be quite brief; I'd suggest you buy this, since there really isn't use for a more expensive one unless you need a tri-pedal. It works well, does not break easily, looks nice, has polarity switch built in, and is as cheap as they get.