Just got it on Friday, so I can't give you a good review yet.
But...
#1 - the Remote is the coolest thing in the world - Nicely (secure) plugs into the unit (which is thin) and has a perfect length cord to the remote. The LCD is very high resolution and a cool blue backlight. Fantastic amount of options - menu is really cool. It may be light and be made out of plastic but it seems pretty sturdy. The three jog dials basically do everything - figured out how to use them without the manual in about 10 minutes. I now walk around manipulating everything with my hand in my pocket fooling around with the remote - that sounded bad.
#2- the iRiver itself is sleak. The top is aluminum but the bottom is plastic. I don't really like that the top is fixed to the bottom by a plastic hinge rather than a metal one - you have to be careful. Nevertheless, it seems well designed and sturdy. The cover latches down really well.
#3 - The batteries last forever (with MP3s, it loads them into memory and stops spinning - kinda freaked me out when I opened it and the disk was stopped). The unit even has the option of discharging then charging the batteries to prevent memory problems. In fact, the LCD shows a little picture of the battery with eyes and a mouth getting filled or draining - cute touch. It also has a AA battery tube the attaches to the unit for extra battery life. I haven't spent too much time with regular cds yet, so I can't tell you how fast the batteries drain.
#4 - the Sound - Surprisingly good. The bass does not have the greatest range (not always clear) but the mids and highs are great. Changing the eq is very effective (Rock is best for me so far - I generally like that scoop). You can apply the eq to both mp3s and audio cds. I have been using it with Grado SR60 headphones which are sort of designed with portables in mind (on problem is with the extra long Grado cord and the long remote cord - I have been binding it up with a rubberband for now). It sounds really good. Look, it is a portable, so it is not going sound drop dead fantastic with every source material, but it is above par (especially with MP3s, which I have generally dismissed as poor quality files). It pumps out enough juice to really blow earbuds out of your ears. With my Grados it gets loud enough that I can hear the music well in all but the loudest of situations, but not loud enough to do damage (which is probably a good thing). Oh, it even has a line out - nice touch.
#5 - I e-mailed iRiver and they told me that they are planning to support Ogg Vorbis (open source audio standard) and MP3Pro in a future firmware release - Very cool.
- That is about all I can tell you now - I have only played with it for a few hours thus far. So far I have been very pleased. For a portable, it is fantastic and fun with a lot of good thought going into one device. Post if you have any specific questions. Hope this has been of help. Check e-bay - so good (still expensive) prices on new ones can be found there.