Pros: Sound, Screen, Interface.
Cons: Proprietary USB Connection
Value: Not cheap; Not expensive. Does the most basic function of a DAP... it plays music... Perfectly.
Audio Quality: Once you spend over $100 on a pair of headphones, your source suddenly becomes the limiting factor in the quality of sound, a distorting Ipod would not suffice, neither would a Zune. I bought the S9 and have yet to hear a legitimate competitor. Custom settings make anything sound as bass heavy as you like, can improve the sound on cheaper headphones, and really make nice ones shine. BBE is better than SRS, better than Creative CMSS3D, Sony CLEAR BASS, DOLBY HEADPHONE, and most any other audio enhancement you can think of.
Design: Buttons on the top of the unit are perfectly integrated, control all playback functions from your pocket, scratch proof screen, rubberized backing.
Battery Life: It is made by Cowon; Cowon, to say the least, does not skimp on battery life.
Interface: User Customizable Interface, made completely of modular .swf files, managed by a launcher set at 24fps, upgradable to 60fps. Store up three or more interfaces on the device at one time, each functions appearance can be modified down to the smallest detail. Faster scolling than an Itouch, Brighter screen than the Zune HD, more adaptable to the user. It's not an apple fed and windows barred prison, it's a palace.
Overall: Multi-Media playback quality is the best. If you want internet, get a phone that does flash; If you want fully functional software apps, get a laptop.