I've only had this a few days, but it's a fantastic piece of kit for the price.
The sound is very adjustable, it's versatile, and the fact I only have to move the treadle to activate it is a fantastic feature. I did have to adjust the off timer to stop it deactivating as soon as the heel went down, but once I'd done this it was perfect. The boost feature is handy too if you use wah mainly in solos. The switch to activate it is on the right hand side of the unit, and I've found that it's possible to carefully use the side of your foot to push it in. The boost only activates when you activate the wah.
The construction, despite being made of plastic, is solid and I can't see it being a problem. Behringer offer a 3-year warranty so in the event of failure it *should* be covered, but I've not had cause to test how good the warranty process is.
The only complaints I have is that there is a slight click when the wah deactivates. This is more noticeable with higher gain patches but, for me, this is no problem really. Also, the LEDs are underneath the heel, so you can't actually see them when your foot is on the pedal, but again, it's a nitpick rather than a problem.
Overall, if you're on a budget and need a wah, I wouldn't look any further.