I have the defender and i love it. Im used to the small clean look but the defender isnt as bad as ppl make it out to be. The commuter is thinner but the problem with the plastic on the outside is that if you drop it, theres a posibility that the plastic will break. Yeah its better than your phone but its kinda but not really like a one time drop and your done. My roomate had a commuter series case and dropped his phone from waist height and the phone was fine but the case snapped.
Just got the Defender 2 days ago and I love it, was concerned that it would be too bulky, it's not. It's sleek, easy to install (video on line) and all functions work thru the case or flaps. The charger / dock port flap took a little getting used to but is fine now. Ordered it from Otterbox and got it in 2 days (in Canada). I rate it a 10 out of 10.
I have had my otterbox for a couple weeks now and love it. The bottom line is Bulky yet it is styled well. I think I'd rather a little more bulk than sleek looks and less protection. I considered the other slimer Otterbox cases, but ultimatley decided on the defender for the most PROTECTION. I could care less about looks. I had a little slim case that I bought for $10 as soon as I got my Iphone4 and I put on a invisishield as it didn't cover the screen. It was sleek, and I was also paranoid about dropping my phone for the whole week I had to live with it! Otterbox Defender was well worth the $29 on Amazon.