i've been using IAD for the last 10 years, and yes, it has improved vastly. the main terminal building is actually really, really nice now. once the trains get moving, i think it will move it a step forward.
yes, C/D is awful. but until MWAA gets their act together, i feel that's what we will be stuck with for a while. once metro goes out there, and the new C/D is built, you can only hope IAD jumps to the top of the list in terms of great US airports.
anyone that experience concourse G can agree, the airport has come a long way.