Welcome to Flyertalk! While the changes have been nice, I don't think its catapulted IAD anywhere near the top of the list (although US airports are generally in such poor shape, esp in comparison to european/asian ones).

I haven't checked the MWAA/IAD site, but I don't think construction is over yet ... the train will eventually be a loop, I thought the first part of what they are opening was a back/forth track. We have some FT members that help out at the airport and others that are very knowledgeable about the inner workings who I am sure will chime in on that point.