Other reviews did a good job describing other features which work super well, so I will only cover the Nike Fitness and Bluetooth to avoid redundancy.
Pros: This nano has all required Nike Fitness components in one unit. No more need for pods on or in your shoes. Yes it even works on a treadmill and tracks Very accurately. Starting out the Nike Fitness, You can select a run by distance, time, or calorie count. During your run, it pauses the music and with a sweet sounding easily understood friendly female voice, gives you a quick update on your distance, then continues to play your playlist. This I found very cool. If you press the top sleep button while running with Nike fitness, it gives you the time, distance and current pace. I tracked this feature and compared it with my Garmin GPS watch and they tracked fairly well out of the box and only improved with multiple calibrations after I completed my run. The more you calibrate it, the more it learns and gets closer to accurate.
Cons: 1)There is one Huge Fail however. The manual suggests placing it at your waist to use the Nike Fitness. Most runners are waiting for a quality workable armband which I believe would compromise this feature based on the how it works. I will test it on my next run. It seems that the Apple engineers aren't runners. This I believe may be a fail for this feature since it is geared toward runners and runners infrequently wear their ipod at their waist, especially because this Nano lacks a clip. I, however, placed my iPod in my Spi-belt which is a small flexible runner's pouch wrapping around the waist. It is a tiny fanny pack for keys, ipods and such. Remember though, it needs to be at your waist, so finding that button while running when it is enclosed in a pocket proves challenging as well. 2)My other concern is that Bluetooth connected to a stereo headset wouldn't work when it is at the waist. Most reviewers and user manuals of higher end sport stereo Bluetooth headphones state that they were required to place their Bluetooth player on their sleeve in order to get uninterrupted playback. My question to the engineers is-since the iPod cannot be at the waist and sleeve simultaneously will i be able to wear a stereo Bluetooth headset and use Nike Fitness at the same time? I would love to get into the minds of the engineers on this one.
I was also successful with Bluetooth connection with my car. It works, but some features are lost compared to when I sync it directly to the radio via USB. With Bluetooth, I no longer can use my voice activated song or artist request which Ford vehicle SYNC systems have. I would instead have to search on my iPod for my favorite song while driving. That isn't a safe option, therefore not making Bluetooth syncing with my car stereo desirable for me. Also, tag information isn't displayed on my car's stereo while using Bluetooth. Perhaps, a car other than Ford has these features.
I am curious about the Bluetooth connectivity with stereo headsets while running. If anyone has success with this feature and where you placed their iPod to maintain connectivity, and quality of sound reply to this thread.