I bought an Otterbox Defender case for my iphone because having two young children who are very clumsy, my phone gets dropped a lot or swept off the sofa if I happen to leave it lying around. I wanted a case that would protect my phone no matter what happened to it.
I bought it online, without knowing how bulky the case was. To be honest it more than doubles the size of my phone, and most people laugh at it when I take it out of my bag. Once you get used to the size though the benefits become obvious. I have dropped my phone on the driveway, from a fair height when it fell out of my pocket and my phone was undamaged.
The outer case is quite grippy, reducing the risk of it slipping out of your hand.
The size is its biggest disadvantage, if you are looking for a slim case then this isn't the one for you. But it's very durable, and well worth the money I paid for it.
I have dropped my phone three times. Once from a height onto my driveway. Not a scratch and no damage. Definitely we'll worth the money!
I had the otterbox on my 3GS for quite a while now. Occasionally, I remove the case to see how my phone looks. It still looks brand new! I dropped my phone at least 3 times. Yes, the otter box may have scratches on it by now, my the phone is still safe and sound. Overall, the otterbox is great if you just want a case that will protect your phone.
What I don't like about this case is the looks. It make my skinny 3GS look fat and cheap. Even though the case has a great grip, I don't feel the satisfaction of using an expensive Apple product. When I put the case on the iPhone it makes the iPhone look very cheap. Another disadvantage is that the otterbox is not water proof. If you accidentally drop your phone is a pool or the toilet the otterbox will not protect it from water.
Overall, the otterbox is a great case for the iPhone if your just looking for protection.