I have Corian, and love it, so do my Mom and sister. Ours are between 8 and 10 years old, each.
My Dad buffs them with a polishing wheel every couple years with little to no mess. They look great, and after being polished, they look new. Nothing is scratch proof. Mom's is the oldest, gets the most heavy use, and I am sure she'd buy it again, except for the comments echoing in her head from the idiots on HGTV about them not being granite.
I wanted Corian because I could get it in a cream/beige color, vs the dark granites that were around when I looked, and I didn't like the idea of lining my kitchen with an earthly stone that is in finite supply and scars the earth to mine.
Gordon