Not very, considering I've had it for almost 2 years now. My micro red dot has a crack in the lens and a dent in the surrounding metal, the wing mount has a nice shiny silver edge around it in places and there are a few bits of rust here and there, on the faux gas tube, upper and lower receivers around the safety, and the fire selector.
From about 3 feet away or more though, you'd be forgiven for thinking I only took it out of the box yesterday. Which is annoying 'cos I really want it to look heavily used =[