Useless to talk in when the sound from the microphone is barely audible. In addition, there are problems with the blue tooth connection, mainly for the left side. Both errors are known and reported frequently on different forums.
Despite several firmware updates, none of these problems have been solved. Now it seems even withdrawn all updates so the original version is the only one available.
The sound to listen to, on the other hand, is good, but not fantastic.
After 2 months they went back today to the deal and the money back.