The PoGo! AudioRave is one of the earliest combined MP3 player/flash drives. It has 128MB of storage, is powered by a single AAA battery, and plays both MP3s and WMAs.
Nowadays the AudioRave is clearly outdated. The player is constructed well, the display and backlight are fine, and it shows track information if that's included with the file (ID3 tag). However, the sound quality of any MP3 player powered by a AAA battery is always going to be poor and the AudioRave is no exception. Even at the maximum volume it's difficult to hear. You definitely need headphones or earbuds that have a volume control if you're going to use it. But more than that, the sound is very tinny, there is no bass, and that makes it a horrible listening experience.
The drive can be carried around without the base that contains the AAA battery. The battery life is pretty poor. On a single AAA, don't expect to get more than 90 minutes of play out of it (it's advertised as 2 hours).
Still, the novelty of having a combined MP3 player/flash drive can be interesting, especially for kids, especially at the right price. Definitely a cool gift for a child or as a stocking stuffer if you can get it really cheap. Even if it's not used for the MP3 functionality, you can never have too many flash drives around!