I have the otter box and love it. It adds just enough size to make the phone comfortable and still fit easily into arm bands for running or my pocket without having to take it out of the case. This version is way smaller then the iPhone 4 one and it better made. I also have a case mate pop! Which is much thinner then the iPhone 4 version. I used to solely use the pop on my 4, but have moved over to the otter box for my 5.
Like I said fits great, looks great, and protects the phone perfectly. Button response is quick and doesn't take much force.