I purchased this in October 2009 and it lasted 10 months and has now been replaced. My bike is parked outside all the time. A combination of the sun, rain and wind have destroyed it. The material it was made of is very thin and is badly affected by alternating sun and rain, which causes it to develop a papery like consistency which the wind then rips to shreds once there is the smallest tear in the cover.
I'm not sure it even deserves 2 stars but the cover was a little too large for my bike which may have contributed to the tearing of the cover, so I have been generous. However the size of the cover has nothing to do with the deteriation of the material it is made from.