First I have to say that I believe my model may be slightly different from the machine described in the other reviews. The only reason I have for saying this is no one else mentions the lack of belt clip. The perfectly slick surface of the player defies any attempt to make it stay by just tucking it in your belt or the back of your pants or anything so simple. A bag for it, or one of those slick belt player holders is almost a necessity if you are going to be athletic. That said you can be very athletic with it, I have yet to make it skip. Trials include violent shaking while at a run, spinning (violently) in hand (the precession alters the disk speed which makes most players skip), picking it up and dropping it 2 feet onto a hardwood floor while playing, and a couple of other tests. Not one skip, and that's while playing a CDR.
The interface and construction is very different from any other CD player I have had. Batteries go inside the player, underneath where the CD goes (you can't see the battery door if there is a CD in the player). The thing is also so light that its weight is doubled by adding 2 AA batteries and a CD. One of the control (G-shock protection) switches is also in the CD area, under the CD. This makes a certain kind of sense as its not something you play around with all the time. On the out side of the device there is only ONE switch, or analog control of any kind, the hold switch. The hold switch is slightly recessed, not somewhere your fingers will go by accident, and controls everything. With the hold switch on you can abuse your player with confidence that the music will keep playing, the setting will remain constant, and that even the volume will not change! This is a major plus, as with the other 4 or 5 players I have had there were always some controls, notably volume, that were not covered by hold. This combined with its phenomenal anti-skip capability would let you listen the thing while dragging it along the street behind you like a pet rock (though that might scar the finish).
The unit has a minimum number of buttons. 8 control buttons, and a open button. All labeled, but keep your manual handy, some of these buttons have cryptic labels, and do double duty to boot. Example "p-mode/ [half circle symbol]" The button controls- book marking, play mode, and repeat. What it controls depends on how long you press it, and what else you are pressing. When you get used to the controls it is extremely slick, but those who don't read the manual will have a blinking 12 problem when it comes to just turning on the repeat.
Sound quality. Sound quality totally trounces the previous players I have had. Sound does not distort. The headphones are a major plus for me, though many will not like the behind the head design. I actually bought this player because of the headphones, and found that they are even better than other behind the head headphones I have had. The design makes it fairly easy to find the 'sweet spot' of placement where volume and clarity are maximized, and the sweet spot is so tight that if the headphones are moved a centimeter, the volume halves and outside sounds can be heard. Again for me a major plus, for others maybe not a plus. Further there are some little rubber flaps behind the speakers which I initially though a major design flaw but later figured out both help you find that sweet spot and also support the headphones by putting the weight (which is very little) of the headphones on an area behind your ear rather than on the ear itself. Once I figured them out, these are the most long term comfortable earphones I have ever used.
If the darn thing could play MP3s, and had a belt clip, I would say that it is the best CD player ever. As it is, its very very good.