I've used this In-Ear systems for around 5 months now, and it works!
Regarding the sound quality: It's not great, but it's okay enough for me. You have a slight constant noice which does not be affected by environmental parameters. I've tested it quite thoroughly:
I'm using it in a fairly wireless setup, where we have multiple monitoring devices, out of at least 2 are of the same brand, together with both wireless microphones and wireless broadcasters from our instruments.
I've also tried it with no other wireless equipment around, including WiFi routers etc, and I haven't noticed any difference in quality, the sound continues to be okay.
The transmitter is really easy to use, choose if you wanna transmit broadcast or stereo, choose a channel and you're good to go.
The receiver is light weight and also really easy. Set the appropriate channel with the buttons on front, turn it on and off with the big knob on the top. This knob also adjusts the volume.
The headphones you get with it are not super good, but since they're connected with a standard 3,5 mm jack you can use your headphones of choice.
I'd definitely recommend this for people who wants In-Eer monitoring but aren't prepared to pay the big bucks
