I've been using these for about 4 years, I have a rs4 and an rs60. One transmitter hooked up the tv and one to the pc.
The quality is pretty good, but don't expect wired studio monitors. I can walk outside our brick apartment house and take out the garbage without losing signal, but going up to the 4th floor was marginal. The 900mhz phone can mess with it too when in use. Most reviews put the sennheisers at the top of the pile. I only wish they'd made the NiMH battery bigger. they only last 3 hrs. Extras are $20.
Sennheisers CS is awesome. I stepped on the rs60's and broke the bridge piece, they sent me a new one for free, not even a shipping charge.
I have found that I prefer the analog tuning ones more than the digital, because as they lose signal they are still audible, but the digitals completely cut out rather than give any static. Another feature of the analog is you can scan for your neighbors 900mhz phone conversations!
I prefer watching tv with these, the stereo effects you'd never notice are in your face, not to mention not bothering anyone else in the room or house who'd rather not listen or is sleeping. I set up RealAudio playlists of NPR programs to stream while I work or do chores, great for things that make too much noise to hear talkradio or audiobooks from speakers.