I picked up the Lifeproof n??d about a week ago. My first impression was it did add a bit of width and height. After using it for a bit, I also notice how muffled the sound is coming out of it, although not bad.
I haven't had the complaints from anyone about sounding like I'm in a tunnel as some of the reviews have mentioned.
The best part about it is the screen is free from any screen protectors.