I used a Seidio surface case for 2 years on my original Droid. It saved my phone from two falls, one onto a hard tile floor, and the other onto asphalt. Frankly I think all these heavy duty cases are overkill. The Galaxy Nexus is a much lighter phone than the original Droid and despite people's claims that it feels flimsy, it seems very solidly built to me. Bear in mind that I was using the holster on my Droid both times I dropped it, and I will be using it on my Nexus. It provides a very solid extra layer of protection, and while I don't wear it on my belt, I do clip it over the outside of my pocket, which keeps the phone from falling out. The only complaint I have about the Seidio cases is actually about the holster, which is that after about a year and 3 months the spring broke in the clip that holds the phone in place, and on my replacement the pin that goes through the middle of the same clip to hold it in place got a bit loose so it doesn't grip the phone as tight as it should. It still works, but considering how much Seidio charges for these cases it's rather annoying. Personally I would recommend buying any Seidio case off Amazon instead if you can find it, as it will usually be cheaper there.
Edit: forgot to mention the two best things about the surface cases. They're REALLY thin, and REALLY grippy. I never feel like I'm going to drop my phone when it's got a Seidio surface case on it, and it adds very little to the overall bulk of the phone.