Notice: I am only talking about the defender series, I understand that the commuter series is a very different animal but I have not seen it personally.
I've been using the defender series for at least 8 months now and I've LOVED it!!! I love the plastic screen protector, I love the shock absorbing silicone outer casing with the rigid interior. Plus the memory foam inside gives that final bit of shock absorbency. The silicone outer casing also grips very well all surfaces that I've tried making it so you can set it on a larger variety of slopes. I don't care what profession I was in, I would not ever want to use this phone without this case! I hate to say this but even my careful mom broke her last phone by dropping it on the floor. You wouldn't ever know by looking at it but I have lost this phone at a full-on sprint on the blacktop road, It bounced and flipped thrice and skidded across the asphalt. It doesn't even have a scratch. It's still just as functional as ever.
The plastic belt holster broke but the company was good to work with and replaced it under the warranty. When it broke the second time I figured that I would just keep it in my pocket. I have never looked but I wish I could find one the same but made out of metal.