I've had a lifeproof for about 10 months - phone has easily survived a number of hard smacks into pavement. The case is starting to look a bit chewed around the corners, but the phone is just like new. It is a bit slimmer than the Otterbox, and not as 'gummy' - so it will slide around on your car dash, but also slide out of your pocket more easily. There is just the slightest gap between the case screen cover and the actual screen - it's possible that's because I actually applied one of those stick-on screen protectors under the case (it was recommended to me as a 'best practice' for an otterbox case I had on my old 3GS - not for the lifeproof, but old habits die hard). I occasionally notice the gap when using the screen, but it doesn't bother me. The headphone jack plug keeps pocket lint out of the jack. It comes with a water-tight headphone jack extender that could be a pain if you used the headphones off and on - I almost never do, so it's no big deal. Also, the case makes it a bit of a stretch to access the 30-pin connector on the bottom, so it may not fit well with some accessories. I think they make extenders - but the auto-kit and standard charging cables I use haven't given me any trouble.
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