I ordered my new Nano on the day of release and it was delivered within 48 hours.
The best aspect of the new Nano is that it is made of Aluminum, which means like the iPod mini before it, its not going to be prone to the same "scratching" issues the the first generation iPod nano was. Apple has learnt from their mistakes.
The brighter display makes album art and photos stand out even more, and still the battery lasts for 24 hours, though saying that, to get 24 hours of continual playback you would need to put the nano on hold to prevent the display turning on, as the display drains the battery. Even with the display on, you can get around 5 hours of slideshows with music.
With iTunes 7, which is a free download from apple.com, you can manage what songs, photos, podcasts, contacts etc are copied over to the Nano even easier than before.
Overall, the second generation iPod Nano really is a five star product, the possible faults of the first generation iPod nano have been ironed out, literally.