I would say that major part of the whole picture is the attention to the details. When flying a sim what is killing me is when looking outside of the aircraft to see a crappy view...
Yesterday I flew one of my first missions in BS and even though I could not do the job, the enjoyment of the flying (as real as it gets on a desk) was great - few elements - The sunset over the mountains worth seeing... the red beacon light reflection on the Vikhr missiles... the shadows on the helicopters... the cockpit lighting...... the list goes on.
So after many years dealing with simulators I will say the BS is the most realistic combat simulation for home computer ever made...
GREAT JOB!