These 'phones are excellent - plain and simple bottom line: excellent.
But you need to be clear about what to expect.
The 'phones are are excellent by the standards of wireless 'phones. You have to be one hundred per cent clear that you are buying the convenience of wireless 'phone technology and that you are not, sadly, in any way at all going to come even remotely close to the sound quality offered by even a £10 pair of wired closed 'phones. Period.
Some reviews complain about the quality of the bass. Clue: there is *no* bass. All the range is in the mid - there is no authentic low or for that matter high. There is no depth to the sound; it often - read usually - has a tinny quality. Accept it and move on to appreciate what these 'phones do offer.
If you concentrate on the fact that you are buying wireless 'phones you won't go wrong. These are the best of the bunch (and I have listened through them all).
The hiss is almost non existant - reviews that complain about the hiss either have an interference high environment or are not using the volume controls correctly. With the RS 140 you need to turn the 'phone volume control down as low as possible whilst turning the television or hi-fi control up.
I have listened to television (and hi-fi radio) through these 'phones whilst using the upstairs toilet (!) - a plaster and wood strut ceiling with no direct line of radio sight - and there is no hiss at all. I have gone to bed whilst listening to Freesat radio (with the connected television being in a different room) with no problems or even occasional distractions.
These 'phones are best for television, spoken radio or popular music radio: you expect little in terms of audio presentation and, concentrating on the visuals or tune quality, you will be more than satisfied.
For all the possible negativity in this review please concentrate on one thing: 6 years ago this level of hiss free quality would not have been possible - not even at ten times this price.
It is an amazing achievement and I would go as far as to say that this is a must buy product of the decade. An incredible bit of kit. Add in to that the fact that you can watch television at a decent sound level late at night without disturbing other family members (or neighbours) and you have something amazing.
Two last points. For television buy the RS 140 (closed) 'phones instead of the cheaper open 'phones. The sound environment is better. You won't regret buying the RS 140. Second - make sure the 'phone batteries are well charged before you settle down and buy some spare Duracell rechargeable 2000ma batteries (which give much better life than the Seinheiser efforts).
Buy them.