I have relatively young children and I am usually pretty hard on my cellphone. So when I got my iPhone a year and a half ago, I immediately researched what would protect it from both me and the kids. The OtterBox Defender was just what the doctor prescribed! Let me tell you, in the year and a half my iPhone has been protected by this case, it has been abused.
I've dropped it down stairs, onto the driveway getting out of my car, off the couch (onto hardwood), off the kitchen table (onto ceramic tile), and the kids are constantly playing with my iPhone. I usually leave the phone on the top of a half wall in the foyer; the wall is 4 feet high with hardwood on one side and ceramic tile on the other. It falls off that wall occasionally. Unfortunately, a couple of weeks ago it dropped off the wall and the piece that keeps the case in the holster cracked (iPhone in case, case in holster). Had the Defender fallen without being in the holster, this would not have been an issue. The fact this has happened previously probably contributed. The OtterBox is is still intact (as is the holster), and the case still does the job of "defending" my pristine iPhone. Problem is that carrying this in my pocket is not really an option for me. As a guy, the holster is definitely the best way to go.
Anyway, I liked this product so much, I've bought another one! Maybe this time I'll take better care, but then again, probably not!
Update: I put in a warranty claim for my damaged case and Otterbox is replacing it. The whole experience was excellent, thus I have upgraded from 4 to 5 stars.