I have tried two different ones from Argos. The cheaper one gave a reasonable picture provided there was no one in the way but did suffer from interference. Because of this I traded up to the next most expensive which I assumed would be better but, unfortunately, I couldn't get any reasonable signal once I was out of the room with the transmitter and, when it had to go though two walls, despite only being about 12m away, it was completely unwatchable!
I have a wireless network but changing the channels on both the sender and the wireless router didn't help. I also have a dect phone but I would have hoped that many people have both of these and any useful sender should be capable of coping with both.
If anyone can suggest any models that they have found actually works I would be very grateful to hear.