I have used several brands/models over the years: Zyxel, Siemens, Netgear, Devolo and now Swisscom.
1. 1 pair ZyXEL PLA-401 V3 Powerline, 200Mbps Homeplug Adapter in a private flat, no problem ever reported for the last two years
Advantage or disadvantage: you do not plug them right into the wall, they have a separate power cord.
2. 1 pair Siemens 200Mbps in a private flat, have been working for 3 years, were recently replaced by Wlan because they all replaced their desktop pc's with notebooks and wanted more flexibility.
3. 1 pair of Devolo dLAN 200 AVplus, HomePlug Network Kit bis 200Mbps + dLAN 200 AV Wireless G Router / 4-port Switch in the home of one of my sisters. The kids were complaining that Wlan for gaming was unreliable, so I replaced the whole network with Dlan.
4. 2 pairs of Devolo dLAN 200 AVplus, HomePlug Network Kit bis 200Mbps for 4 PC's + dLAN 200 AV Wireless G Router / 4-port Switch on the second floor of an office. The house was built in 1950, but that was not a problem. Works very well, but one device broke after 2 years and needed to be replaced.
5. 1 pair Netgear XAVB2001, 200Mbps, ECO, in the home of a friend, have been working for the last 2 years.
6. 1 pair Swisscom brand (Swiss telephone company) 200 Mb/s (probably Siemens) installed yesterday in the home of my other sister. This brand has a fixed encryption key that cannot be changed. All other brands you can change the encryption key by pushing a button for 1 to 10 seconds. They have the router on the ground floor and want to connect a Digital TV set on the first floor.
They all work pretty well, but I have to say that none of these users (except the kids) are power-users and don't care for maximum speed and they do not stream. Personally I do not use them as my home office has been cabled long ago. None of the different brands ever made any problems except 1 Devolo device that broke. And it's really easy. Set-up time 5-10 minutes.
If you add a 3rd or 4th device you can transfer the encryption key to the new ones by pushing the button for one second on one of the existing adapters, then go the new ones and push the button there for one second within 1 minute.
If you buy new ones, get the newest generation with 500Mbps speed. Hope this helps.