I've been using them for about 18 months. They have their moments but overall I am quite happy with them. I am using mainly TP-Link. Orange in Sydney have them at quite a reasonable price. See
I also have a number of Billion Powerline adaptors which are quite hard to get hold of but interoperate well with the TPLink's and have a model which doubles as an 80211n access point. Will stream standard def video from a mythtv box and via vlc from a dreambox without problems. Haven't tried HD.
Your mileage may vary. Apparently they may not work across different circuits, though I have not found this in quite a large house. You also should be aware that the next generation is faster though no doubt correspondingly more expensive, at least initially.
I have one more remote area of the house where the adapter is hooked up to an old netgear 4 port switch which runs two pc's, a voip telephone and a network printer quite successfully.