Simply the best portable audio I have ever listened too, but by no means the most intuitive or easy to use.
Straight out of the box it isn't massively different from other comparable products, the sound is average, although possibly a little clear...Read moreer, but definitely not brilliant. Where the cowon really comes into its own is the equaliser settings; they are beyond compare at this price range. As long as you take the time to set them up - there are four user settings and about thirty presets - it makes listening to music a joy.
Setting up the equalisers can be a bit daunting if you are fairly new to it all, however there are plenty of websites offering advice, and at the end of the day no-one can tell you what sounds best for your ears, you'll have to experiment.
The interface isn't particularly intuitive, however you can download others online that make it a little easier on the eye. The screen is vibrant, although not as good as a Zune HD, and it's not as crisp as the new iPod touch, however it's definitely not bad, merely adequate.
Overall, it plays music fantastically, as long as you take a little time to set it up, it plays videos adequately (in the right container), it displays pictures adequately, and it streams music to Bluetooth headsets just fine (quite why you would is beyond me, the sound suffers as there is no apt-x codec support)
One last note, the bundled headphones are, although better than the iPod bundled ones, not particularly good. A player this good deserves a good set of cans!