Well, I got my gel case (in grey) from seller Ashophone.
First off, it was a real pain to get on. I seriously could not get it on correctly until I sort of loosened up the material slightly by bending it around with my hands. The problem is, the gel material really clings to the smooth chrome on the back of the iPod. I mean, it REALLY clings, so you can't slide it in at all.
I had to slide the top in, and by slide I mean, push pretty hard, back and forth to inch it up into there flush. Then from there I worked the sides on, and finally pull the bottom corners over.
As far as fit goes... there is a little extra material in the top right corner (near sleep/wake button). Not much, but you can see the case curve out slightly in that corner. Not enough to bother me, but it is what it is. Honestly without that slack I'm not sure if the case could have gone on at all.
Because it's see-through, you get the usual watermarking on the back. Looks like fluid is trapped between the case and iPod, and I guess it is just inevitable moisture that gets trapped in there. Not sure if there's much you can do about it.
The sleep/wake button presses just fine, but the volume button are a little weird. The case kind of cuts down on the haptic feedback you receive. And it's one big button that sits over the two separate buttons in the touch, sort of doing away with the advantages of separate buttons. Easy enough to press with your pointer finger when in the right hand, not as easy to press with your thumb when in the right hand. Maybe it's just the angle.
Camera and mic cut out is big enough that even if case is off center, both remain unobstructed.
It slides in and out of the pocket nice though, all while feeling grippy in your hand. That's the nature of this material, and one of the advantages of it over silicone.
My case search is not done, and at some point, I may break down and get a "real" case (belkin/griffin/incase, etc). But for now this will serve me fine. Good for 2 bucks. But a pain to get on, might be a pain to get off, and fit is so-so.
