I'm running a Buttkicker on my TrakRacer setup which doubles for flight simming. It makes a huge difference. If you get it set up correctly the aircraft moving along the tarmac, the landing "bump", gear up and down, etc are all "felt" along with the vibration of the engines of course. But for me the most realistic feeling the Buttkicker conveys is when moving along the runway at speed and when landing. The feel - no kidding - is all but identical to landing in a real aircraft if you have it set up correctly. Incredibly impressive - and I am just using it connected to an audio output. There is much more complicated software you can use with a Buttkicker but for flight simming, for me at least simply connecting it to the audio output is more than sufficient.

Mind you, I am using A2A Accufeel which adds additional sound details not available within the default sim and this makes a big difference in the performance of the Buttkicker. One example is the tyre "chirp" when landing. This is very badly done in the default sim and the A2A Accufeel makes all the difference here. And with the correct tyre sounds conveyed, the Buttkicker will also elicit the correct response in terms of the physical sensation. 

Yes, it is fabulous, I would hate flying without it now. I had a buttkicker, but I think it overheated or blew fuse. I upgraded to the Pearl Throne Thumper which is fantastic. Never gone wtong, and to make sure it stays cool I bought a little desk fan on eBay and mounted it to blow air into the vents. It cost me £250 but since I have a cockpit build, I just added it to the bill. I've got it attached under a car seat I use, but the clamp is built for drummers stools or office chairs. 

Jon, Ive never had much luck getting that 'kick' or 'bump' from the landing with a buttkicker. I too use Accufeel. Do you have any suggestions??