i'm into my second season now and i can't see any change of color or deterioration like cracks, stains,...it's very good quality.
But then when i'm finished using it i wipe it off and place it back in its bag and keep in my garage. In the winter i lay it flat on a table in my basement, deflated. When on camping i left it inflated under the sun for a few days.
If you are going to leave it outside when not in use, i guess you should keep it in the shades and protected from the rain. Don't know about the winter though, if you have one of course.