When I got my new iPod classic a few months ago, I decided I definitely needed a case to protect my new baby from scratches and getting broken rattling around in my bag.
I opted for this smart case from Belkin, in a pretty light/bright green colour. I bought it on Amazon Marketplace and at the time it was some ridiculous price like 1p plus p&p from Germany of around £7. So overall pretty cheap as far as iPod accessories go. It is now for sale directly from Amazon for £13.99 or on Amazon Marketplace from £10. Aside from the green I chose, the case comes in black, silver, clear, blue, pink and probably more which weren't available where I bought mine. For the coloured versions, the front is coloured brushed aluminium with the back clear acrylic.
The version I bought was made specifically for the new iPod classic 80 and 160GB models. I can't say if any other versions would fit it, my guess would be yes but they might slip around making the controls hard to use if the case is too big as it's rigid-sided. I know Belkin do make similar cases for the new Nano but I'm not sure about older models.
When I opened up the packaging and put my iPod inside, it slipped in easily and the cover clicked straight on without having to line it up. Definitely not as fiddly as I'd envisaged and as I'm always taking it out to pop it on top of my speakers this is a major plus because it takes no time at all.
My initial impression was that the case was well made and tough, you would definitely have a job trying to damage your iPod through this (although not so sure why you'd want to!). The screen, however, does get scratched quite easily. I suppose it's good to know that the screen of your precious iPod has been spared those scratches, but it makes watching videos a little frustrating at times, although not impossbile even through fairly scratched up areas. Mine has been abused quite a lot carrying it in my bag when I'm on the bus and the scratches don't bother me at all when looking for music, etc, I just pop the front cover off when I'm watching a movie.
Probably the reason I chose this case over some others is that the headphone socket and dock connector are accessible while the case is on. Great for transferring music, charging, etc but you would probably have to remove the case to fit it onto speakers as it's quite bulky.
The bulk really is my main issue with this. Part of the reason I love my iPod is because it's so small and light, but the case makes it weigh at least twice as much, and you would have a definite pocket bulge if you carried it that way. Considering the metal front part is aluminium, the overall case is pretty heavy). I tend to use the case for listening to my iPod when I'm carrying it in a bag where I know it will get bashed around, otherwise I go without.
The clickwheel also loses its sensitivity a lot inside the case. Sometimes it's fine but the case is a little too big (probably as I have an 80GB I daresay it'd fit the 160GB more snugly) and so the iPod sometimes slips to the back of the case, meaning the clickwheel part of the cover doesn't touch it. It can be annoying as the wheel is generally less sensitive/sluggish inside the case but sometimes it completely won't work while scrolling (clicking is okay). When this happens I generally reach the iPod from the dock connector hole and push it up towards the front, but it's a little annoying.
Overall, I probably wouldn't buy the same product again as there are so many other versions of the same thing which might not a) scratch as much and b) be quite so heavy! I do think it will last probably the life of my iPod, though, and it has definitely kept it clean and protected, not a scratch on it, so if you don't always carry your iPod in your pocket the extra bulk might not bother you.