I was very  sceptical about the concept of network over power but was in a fortunate position to borrow one to try out.  I was pricing up the N adapter for my 360 but though this might work.  
 This product is fantastic, no set up required.  All I did was plug one into my router and one in the 360 and it just detected.  Fantastic Speed, updated all firmware in 20 minutes and I don't get any dropouts. 
 
Any one considering using one of these in the future, i would highly recommend it.  Only downside is that you can't run it though a power board.