I initially went with a case on my iPhone 5 when I got it in February because I couldn't find a belt holster I liked for a naked device. I could only find case/holster combos. So I went with the one Verizon sells. But I finally got a holster for a naked iPhone, and I'm happier.
The case isn't a complete write-off though... While I was using it I got a ProClipUSA car mount for the iPhone with a case, and I'm using the bottom section of the two-part case permanently mounted in the car mount to hold the phone.