I've been using powerline adapters for some years now. I had some cheap DLink ones when it was still a fairly new concept, they lasted around a year but they got very hot and I suspect they eventually failed due to overheating. I now have a pair of Linksys PLE200 adapters which I've had for maybe 2 years, they're on 24/7 and have been very reliable for me.
I don't do many LAN transfers so the only thing they get used for is my internet connection, so I can't comment on the speed though mine are rated for 200mbps - my DLinks were 14mbps I believe as they used the first standard for Powerline networking.