I have watched these forums for a long time and gotten great advice but never felt compelled to post anything myself. That changed when I got this case and I felt I needed to share my experience since many have been asking for impressions of it.
I ordered directly from lifeproof and got my case on Saturday and couldn't wait to finally cover my naked phone. I had high hopes for this case as others have really liked theirs and I spend a considerable amount of time on or near water. I followed all of the instructions on their website (unlike the 4/4S case which had instructions in the box, the fre simply points you to their site). The case passed the water test with no problems. I inserted my phone and set about my day. Shortly after that the issues started.
First, I have no rainbow effect and the pillowing is minor. The gap does make navigating somewhat more difficult but it was a sacrifice I was prepared to make for the sake of having my phone protected from an accidental drop into the lake, fishtank, or pool...all of which have happened to family members over the past few years.
The big issues I have are with the proximity sensor and microphone sensitivity. (I carried my phone naked from launch day until Saturday so I know these issues are case-related.)
During one of my first phone calls, I started getting a ringing in my ear that could be heard by the person on the other end. The sound was like you put a microphone next to a speaker and turned the volume up. Terminated the call and tried again. Same thing. It does not happen on every call, but at least 50% of them. I have tried adjusting how I hold and use the phone but it still happens. When there is no ringing/feedback, the person on the other end often complains that I sound muffled or that the microphone is cutting in and out. I feel like I am yelling into my phone for them to hear me. All of these are totally unacceptable side effects which make phone calls a chore.
Another big problem is the interference I'm experiencing with the proximity sensor. Sometimes the screen will light up during a call and I'll be "face-dialing" without knowing it. I have accidentally initiated several facetime calls, dialed into people's ears, and even inadvertantly muted conversations. Other times, when I pull the phone down from my ear, the sensor will not recognize it and won't light the screen. While this is a minor annoyance, it's something that didn't happen before the case and definitely not a welcomed addition to my iP5's functionality! It may not be a big deal for some, but it's not something I'm prepared to deal with.
I took the phone out of the case this morning and everything is functioning properly. The case is lightweight and waterproof, but that's all the praise I can give it.
Oh, and for those of you wondering, the headphone jack is very recessed and I haven't been able to find any cord small enough to fit in the opening on the case. IMHO, the included adapter is the only reliable way to use headphones or other audio devices (and its the only way to ensure your phone is protected from water and dust infilitration). Although for me its another annoyance to have to keep up with the adapter and remove and replace the plug for each use, that's something that will be a personal decision on whether the hassle is worth the protection. Not a deal breaker for me, but when added to my other issues, it certainly doesn't help.
After struggling with this case for four days, I'll be sending it back to lifeproof for a refund. Of course they will keep a 15% restocking fee plus shipping costs, which is irritating when their product does not work for me, but that's a small price to pay to get rid of what I had hoped to be a great product. I'm disappointed in this case to say the least, and I'll go back to running my phone naked until I can find a suitable case.