I got the otterbox defender today and it is causing me to fall out of love with the iphone 5.
The case is a huge, overweight brick. Some problems I've noticed immediately with just light use:
-typing is difficult because of the massive thickness of the case
-the screen protector makes the touchscreen very unresponsive
-the bulk and size make you feel like you're carrying a phone from the 1990's.
I guess I'll use the defender for the next few days as I shop for a lighter, more user friendly case.