Before saying anything else: With regards to what this pedal actually costs, it's a great buy. You need an expression pedal, you cough up a fistful of euros, you've got one. Period. That could end the story, but let's look a little closer.
Made of plastic, the pedal is very lightweight, which in my case (as in pedals case) is quite an advantage. It will spend its days well protected in there, so the plastic housing won't get too damaged. However, if you plan to have it as a standalone, I'm a little concerned that a plastic pedal could prove to be too brittle.
It responds nicely and seems more robust than its construction would indicate. However, the main drawback is the short scale of the pot itself. The distance between full up and full down isn't very long at all, and might be a problem if you need more precise modulation.
But to sum up, I'm glad that I bought it.