This unit got me back into the MD scene, and this post actually made me get out of the wood work and register!
I've got a bit of a history with MD - it started with the DR7 which is something of a legend for its sound quality. I got an NH900 for the convenience of Hi-MD when it came out, and it's sound comparable - and I find the RH10 even better. It's certainly different from both the DR7 and the NH900, but my young ears couldn't go into much more detail than that
The build is very solid while remaining small feeling in the hand. It's absolutely gorgeous - I got me an orange one from Japan (worth it for the LCD remote, I think).
The best part of the unit is by far the screen - that OLED (I think is the term) blue text is perfect for all conditions, and navigation on the scroll wheel is pretty easy.
The most common complaints I've heard about the unit are that native MP3s sound awful (I wouldn't put it past Sony to have screwed around with the playback to make ATRAC sound superior) and that the unit scratches easily. Also, most people would sooner lop off their right hand the voluntarily use sonic stage, but it... works. Sometimes
Personally, I'm extremely satisfied. I thought about getting an HD based player for capacity, but as my music collection has grown to about 50 gigs and shows no signs of slowing, I realized that the difference between a few gigabytes and a few dozen gigabytes isn't all that significant with so much to choose from in the first place.
And of course, recording is great - PCM is an awesome option! Live recording is really where MD as a format shines, and this unit is no exception.
And it's pretttyyyyyy