I've heard these things overtime fade & becomes discoloured....especially in areas where you get harsh winter conditions & alot of road salt is used (which I have seen & it's looks aweful). I had the chance to put them on both my ES's, but decided to pass. Pretty pricy item too for such a small area that's being covered imo.
I agree with mburn, you do your best to keep the finish in great shape (wash/wax often, never get behind a gravel truck etc lol)......but over time, you will get dings, chips & the occasional dent.
Put that $600 towards a good set of tires, or 16" rims for winter rubber or part of it to a nice tint job (which does wonders for appearance). Just my 2 cents.