It's funny, I just had a great experience but I probably had a somewhat unique perspective as I was there on a connecting flight. Flew into the A terminals on a UAX flight with enough time to walk about half-way down the International terminal. As it was mid afternoon, the place was pretty much deserted.

On my return, my connecting flight had a two hour delay so I got a longer walk through the International terminal. Got to do some plane spotting and peeked into the lounges through the glass doors.

Was my first time in IAD (since I was a teenager heading to HNL). I thought it was pretty nice. Of course, I didn't have to go through security or encounter the mobile lounges.