I must report that I am less than impressed with the stability of my second-generation Nano; I’ve had it for about 2 weeks, use it every day when I run or at the gym. I’ve had to reset it (by holding the Menu and Select button for a few seconds) on several occasions. It usually happens after I install or remove the Nike+ sensor. The problems range from the loss of audio through the headphone even when the LCD looks like it’s playing music, to messed up sound (like really bad FM radio, or how my car radio sounded like when my antenna was stolen), to just not coming on without resetting it first. For the record I have a 2g 2GB iPod Nano with firmware version 1.1.1 optimized for Macintosh.
This is my 5th iPod and my previous 4 were a lot more stable than this. Well, my 4g 40gb iPod had the high-pitch noise problem when the HDD spun up, only noticeable with high end cans, but I never had to reset the thing.
Also, when I go to Nike+iPod -> History sometimes it takes a good 10 seconds to load my workout history, what gives? I am pretty certain these are pretty much all software problems so I am hopeful that the next firmware release would fix them. Either that or it will be going back to Costco.