its easy, the hardest part is NOT tearing up the doorpanel. just go slow when popping out the clips. I use a long flat head screwdriver and a flashlight.
its not hard....make sure you have a long magnet to pick up the assorted cotter pins and such that you *will* drop inside the door. also, might want to wear long sleeves unless you want cut up arms. oh, and somehow secure the window in the up position, duct tape works nicely, otherwise you'll end up with it coming crashing down on your fingers when the regulator is removed...ask me how i know
All as said above.
The smaller the hands you have the easier it will be. Hardest part for me was adjusting the damn window once I had it all set up and in place.