Secures itself very well and the material is not thin at all.  Offers great protection and adds style to my home.  Barring a strong hurricane-like storm, I have no worries about this withstanding anything Mother Nature can throw at it.

Pros: Very high quality material.  Vents definitely provide peace of mind during a wind storm.
Cons: It's not exactly inexpensive but you're definitely getting what you pay for.  Color options would also be nice to match existing covers.