I use it for almost three months to record rehearsals and concerts, and every day as a mp3 player.
I was using previously an MD, much less practical (larger, heavier, proprietary format, etc..).
What I love most: the autonomy (remarkably despite the use of a single rechargeable battery), featherweight, and especially the ability to save all the recording parameters (size, quality, compression, sensitivity, etc.). and recall a single click depending on the context (low quality for repeated, high for concerts, etc..).
The sound is excellent. But note, you hear every detail. This is great for concerts, especially as in this case it is easy to position the camera (opposite the group on a microphone stand). However it must be repeated in many trials before finding the right location, good location, good settings, etc..
[Edit 03/12/2010] The screen is small. Some details are difficult to read, especially in concert, when lighting conditions are not optimal.