Pros: Good range, nice sound, mostly hiss-free
Cons: Can start hissing suddenly, in electronically noisy environment head position changes reception
The RS120 is a wireless headphone that receives an analogue radio signal, as such it is prone to interference from cellphones and is easily shadowed by having a TV or other shielding things in the signal path. This said, when they are getting a clear signal and the source is line-level and not amplified as from on-board sound from computers, they have no hiss while playing music and reaches ~50 m from the base-station without much distortion.
The sound is very pleasant, it is slightly rolled of at both extremes of the sound spectrum and there is a slight mid-bass bump giving the phones a warm tint. The level of detail is what you could expect from phones like these, good but not great. Positioning is okay, the drivers are angled witch gives a certain depth-perception but it is still a small sound-stage. These headphones are very forgiving of recordings and i sometimes prefer them over my k701s.
These headphones are great for watching TV and listening to music while doing the dishes or sitting outside in the garden. They are a supra-aural design that is extremely comfortable but they have very little pressure on the ears, this means that they are prone to fall off your head when leaning forward.
All in all these headphones are great for the price and do exactly what they are meant to do. I have owned these for 3 years and they have withstood being dropped numerous times without breaking so the build-quality is great.