It isn't often that hardware manufacturers find a new way to boost online gaming performance. This makes the KillerNIC M1 a bit special in it being a completely new approach to increasing FPS and reducing "lag and latency". The way the KillerNIC functions makes it quite versatile and it can do a lot of different stuff besides boosting online performance.
One of the downsides to the FNA applications is the quality of them especially the BitTorrent client needs some work before it's up to specs with i.e. uTorrent or Azureus. Of course the FN Torrent client is good enough for the everyday tasks, but the lack of some of the more advanced functions, which makes it less suitable if you want to share large files like family photos or videos.
Performance of this card impresses with an average FPS increase of almost 25 FPS in CS:S and 10 FPS in BF2. This card has the potential to provide a smoother game play to lots of people. Another thing worth noticing is the fact that the hit registration and latency to and from the servers were decreased a bit compared to a normal network card. I'm sure that latency will be decreased even more when a slower connection than mine is in use.
The biggest obstacle in widespread use of this card is definitely the astronomical price of $249. While it seems to be fair for the hardware used on the board, the features given and the low production volume, it limits the possible users to hardware gamers and enthusiasts.