I have to say, I prefer the previous model rather than the new one, for a variety of reasons.
One of the things I didn't like about the iPod Shuffle was its reduced size. Now, this might be an asset for you if you like things that are super-small, but for people like me who lose things in the blink of an eye, it can be more of a problem than a feature. The day after I got my iPod Shufle, I lost it because it was so small. It ended up at the bottom of my bag, underneath a few heavy items, which can't be good, even with the aluminum casing.
The controls were also kind of annoying. I liked the previous model because I was able to change the song with the iPod in my pocket; with this one, I had to find the little white bar on the earphone in order to change the song. Also, it was kind of hard to remember how to change the songs, change the playlist, etc., because you have to press the bar in a certain pattern to make it do what you want it to, and I couldn't remember which was which. I suppose you would get a hang of it after a few days, though.
On the other hand, I liked the new clip on the back of the iPod, because of its tight grip. It was much harder to pull off of my clothes, so it has less of a chance of falling off accidentally.