I use it for a month and no problem for now. I wanted an mp3 player with Flash memory to avoid breaks in crashes, an FM tuner, a USB2 port for acclerer transfer rate and above all compatibility Ogg Vorbis.
It is more expensive than a USB key MP3 player, but iRiver is known for quality audio. It's a good price quality (512 MB to 166 euros)

Pros:
Audio quality with headphones Sennheiser (rare on this type of products)
Firmware being updated fairly regularly.
It is compatible with Linux firmware UMS (seen as a USB key)
Good battery life (15 hours with a battery R6)

However, it is regrettable:
the ergonomics of the device that is far from being exemplary (the grip is far from being intuitive and must be sought in the doc to dplacer in menus)
the FM tuner of average quality (20 stations mmorisables)