Jay, thanks for getting this back on topic. IMO, Congressional (Blue) is a good golf course, but a GREAT club. (Full disclosure, I worked there in 2003 and 2004, and left because 1) I missed the NJ/NY/Phila area, and 2) I was passed over for a promotion).
I think the question you are asking is a bit broad-are you asking this from the perspective of, say, average member play, top amateur, or professionals. Because I am currently a 13 hcp, I will answer your question from that perspective; when I played the course regularly, I was maybe a stroke or two better.
Conditioning-wise, the course is in immaculate shape, thanks to Director of Grounds Mike Giuffre and his crew. When I was there, each course (Blue and Gold) had its own Superintendent, and a large staff. In an area such as WDC, with varying and severe weather patterns this is not a small task. The presentation of the course is better than excellent.
I recall there were established, written standards for the courses, defining all details, established by the greens/grounds committees, and a professional architect was retained for each course-Rees Jones for the Blue, Arthur Hills for the Gold. I do not know if this has changed since 2004. I have a high opinion of this because to my way of thinking, it ensures standard operating procedures and consistency in presentation and playability.
Architecturally, I felt the course was very one-dimensional; by that, I mean the basic modus operandi for most holes was a high, straight drive and a straight mid to long iron to most of the par fours. I did not feel the fairway bunkering in most cases defined the ideal side of the fairway to approach a green from, or functioned as a sentinel, warning players to keep away. In most cases, I think the greenside bunkering was the same-it did not necessarily push players one direction or another, in some cases, seemed purely cosmetic to me, rather than strategic. When I look at an aerial of the course, yes, it's been 7 years, but I can recall many details. I do seem to remember the greens were divided into well defined areas or sections, but not very severe in terms of spines, slopes, etc. I do not recall the greens being oriented one way or another to better accept a specific shaped shot, or repel an indifferent shot, in most cases.
I do recall many areas where flags could be tucked behind bunkers or placed in proximity to slopes, to make getting to the hole a challenge.
Having said that, the challenge of the course is accuracy; straight driving and straight, controlled long iron play. There are a few holes where one could turn the ball-maybe a draw on 1, a cut on 4, a big draw on 5, and a draw on 12, maybe on 16, but 5 and 12 are really the only holes that bend considerably.
There is a fair amount of containment mounding, which I am not sure the placement of which is for spectators, due to the architect's tendencies, or the membership's request. I do recall chatting with a member, who said words to the effect of 'Rees Jones believes a good shot should stay on the golf course' (or words to that effect; do not quote me or use this as an excuse to bash.)
I will be back later to go through specific holes.