I do like their durability, but I cannot make myself get one. I don't like the way they make the iPhone 4 look.
I love a naked phone, but a bit uneasy about having it naked for too long. The "Apple" bumper I bought from Amazon (turned out to be a Chinese knock-off) is already tearing from use (I have an older iHome I use to charge my phone at night, and have to remove the bumper nightly and put it back on daily... I loved the bumper but worried that so much putting it on/taking it off will do the same to the brand name product too.)
Right now I'm just using a clear plastic case that covers the back. Very basic protection :/