Bjorn3D has reviewed a 4GB Apple iPod nano:

I usually avoid jumping on bandwagons, but I've crawled aboard the iPod bandwagon and am glad I did. The 4GB nano is a great little DAP and photo viewer. I am by no means an authority on DAPs, but I strongly suggest giving the nano a closer look if you want a flash-based DAP. Apple offers the nano in three capacities - 1GB, 2GB and 4GB - and two colors - black and white. Both colors look about as slick as a DAP can look. Plus, the user interface and Click Wheel are excellent. In addition to the great style and interface, the nano offers great little extras, like Contacts, Games, Calendar, Stopwatch and much more.

Pros:
+ Excellent user interface and menus
+ Click Wheel rocks!
+ Great looks
+ Great features
+ Decent battery life
+ Colorful, bright display that's easy to read

Cons:
- No WMA support
- Included case could be much better
- Surface could be more scratch-resistant
- No FM tuner
- Screen could be bigger (longer at least)