I've had one of these for a couple of weeks now and so far, it's fantastic. When these came out, I thought it'd be an ideal time to replace my old 2nd gen Nano.
I cannot fault the design at all. It's very similar to the design of the 2nd gen Nano in ways and it's very sensible. I don't know why they designed the 3rd gen Nanos the way they did... it was taking a step backwards. The design of this Nano is excellent. It is a good aluminium casing, which doesn't get covered in fingerprints and doesn't scratch easily (the colour choices are fantastic too!), the screen and click wheel are well placed and the screen is the perfect size. The curved design works tremendously well... in width and height, there's hardly any difference between this and my 2nd gen Nano, but the curved design makes it feel a lot smaller. It is easily small enough to fit in the pockets of all my jeans.
I found set-up to be very quick and painless - I was ready to go with it in 15 minutes. Obviously, I already had iTunes installed, with all my tunes on the program already, so that sped things up, inevitably. But, if my experience of setting up my first iPod is anything to go by - that was quick and painless also. I believe it took me between half an hour and one hour (including installing iTunes, adding my songs to the library and loading everything onto the iPod). Battery life is quite good too. I use it for approximately an hour and a half a day, 5 days a week and so far I've only had to charge it once (yesterday).
In terms of using the device, it's ever so easy. They have kept things pretty consistent, so it didn't take me long at all to adapt to using this one. I'm sure that first-time users will also find it very simple. The menus are clear and intuitive, the click wheel is very user-friendly (ever so slightly too sensitive, but it's by no means a problem) and you can listen by album, artist, genre etc, which is great. The new shake to shuffle feature is a good one, though I can't say I've used it much, as I tend to listen by album. The cover flow feature is a nice one, though nothing particularly special. It's a nice alternative way of scrolling through your albums, but it's by no means a necessity. I do, however, love the feature that if you turn the Nano sideways when viewing photos or videos, that it flips the view to be horizontal - it's extremely handy and really enhances viewing. The screen is also sharp and bright and renders colours very well.
Onto the most important thing - sound quality. I've found it to be ok. It's not brilliant, but it's no worse than on my old Nano. The volume level is set too low, in my opinion. I've tried setting it higher, but it just reverts back as soon as I exit that screen. I have to have it at almost maximum volume most of the time if there's any kind of noise around (normal traffic, lots of people etc) to get it to sound decent, which is a bit of a pain really (there's nothing wrong with my hearing). It's the only reason I've dropped my rating of it a star. Still, having said that, it's good enough for me. I'm not looking for home-audio-system quality... just something that sounds fine and is easily portable so that I can listen to music while on the move and it's brilliant for that. The 8GB capacity is perfectly adequate for my needs and I think it's a competitive price. In my opinion, this is a great little gadget and I'm very happy with my purchase.