After using the new 2.1 firmware for my Nomad Zen Micro for a couple of days, I can see why they haven't upgraded all their players en masse quite yet. It still has a few rough edges. Red Chair Software, makers of the awesome Notmad Explorer that I use to manage my other Nomads, advises that you use the older 1.x firmware "you have a specific reason to switch". Of course, I have a very good reason to switch. The 2.1 firmware is actually beta - something I think Creative should make a little more obvious on the website (not that I wouldn't have downloaded it anyway). For the less adventurous, the 2.0 firmware also supports Napster to Go and isn't in beta.
The place where I notice the rough edge the most during song transition. When I push next or previous song, sometimes it happens right away and sometimes it takes 4-5 seconds. It doesn't happen when it's playing back a set of songs - what ever the Nomad is doing (verifying licenses I'm assume) it must do it for the next song before the current song ends, so the lag only occurs when you're jumping around manually.
That's really my biggest complaint. Napster to Go works really well. They haven't upgraded their help files to the new 3.x version of Napster - for example, all of their screenshots have a separate library function within Napster, but on my machine it just uses WMP's library - but it's pretty easy to figure out. I've configured NTG and WMP 10 to auto sync any Zen Micro with any songs I've downloaded from Napster (about 1GB in the first 24 hours I've used it!). The only complaint there is that autosync works by playlist. If you download a Napster compilation, autosync will transfer the music but not the playlist.
And that reminds me of a feature I'd like to see on the Nomad (all of them). I want to be able filter the list of album to exclude the ones that only have one or two songs. When you download a compilation, you get around 25 songs from different artists. Great for discovering new music, but it adds a bunch of noise to the list of albums. So why not exclude albums that only have a few songs downloaded?