Our Diamond Shield looked perfect after 10 years. When I see posts complaining about it I notice that the majority live east of the Mississippi or in humid areas. I think that's one of the problems. Another is poor application. The product, itself, is good.
Our travels were in the dry West. We also took care of it - always used a protectant and kept it washed with no bugs left on it. On our all summer trip to Alaska we had to wash the front daily for all the bugs. It certainly protected the front of our motorhome and it was perfect when we sold it.