I've recently bought one of these kits. They're simple to install, but I've noticed the unit with 3 ports on it makes a constant high pitched whine or hum which unless you have the TV or radio on quite loud tends to get on your nerves after a while. I've got a support call in with Devolo to see if this is normal or not. The unit has several cooling vents, which I assume is to cool the unit as it has a built in switch, so maybe it's just the sound of all the electrics, all I can say is a couple of old D-Link units I had (that only had one port in each unit) were totally silent, so unless you don't mind the constant whining, you may want to consider something else. I'll update this if I get any joy from my support call to Devolo.
Update 1. Devolo have mailed me to say the humming is not normal, so I've ordered a replacement with Amazon, sadly a 1 - 3 week lead time now.
Update 2. A Few months on and the replacement has been working fine, so just one dodgy unit, speed and simplicity of installation is great!
Update 3. Its now October 2012, and the 3 port unit has now failed like others. The plug works so the fuse hasn't gone, but there's no lights on the networking part at all, so its going back to Amazon again....a shame that the hardware seems to be a bit flakey.
Update 4. November 2012. Amazon were kind enough to quickly send a replacement out again, and so far the new unit is working OK, but the long term life of these products remains a bit of a concern!