I bought the sim the other day. I've thousands of hours in MS Flight Sim and Shuttle Space Flight Simulator and I'm in the aviation industry, so the checklists and procedures weren't too alien for me. I've completed STS-1 and STS-8 and am about to start my next flight. I guess the biggest challenge for me has been RMS operations, and I can't quite get my head around how to move it with my joystick, so I've been sticking to the NUM pad.
Anywho, great work on the sim. I highly anticipate the next release.