Okay, I've slept on this one. I'll set out some comments for discussion (before Matt O'Brien gets on here with his caddie lore) that point out many of the positive features about Huntingdon Valley. I'll predicate these comments with one note; While Joe's labels of the holes in terms of the A-B-C are correct, it is more common to consider the A-B routing as holes 1-18 with the C routing as holes C-1 through C-9. I apologize for the change in format.
Routing
Tom Doak's comment (in the Confidential Guide) that the golf course was routed by Richard Petty is at best a veiled cut at a seemingly formulaic routing and at worst bad humor. In order to really understand Flynn's routing, one must look past the routing of the nines and look at the topography. As is perhaps apparent in the photos, the course is routed through a Southwest to Northeast valley that ends at the clubhouse and splits North toward C-1 Green and Southeast toward C-3 Green. When facing the A-B nines, the holes either lie on the South facing slope I call the "Right Side" or the North facing slope called the "Left Side." It is through this dichotomy that the purpose of the routing becomes apparent. With the exception of holes 1 and 16, the right side holes are the least severe in terms of fairway slope and awkward lies. This is perhaps most apparent on the A nine, which is routed further up the valley bowl than the B nine.
The left side holes feature some of the more demanding tee shots on the golf course, shots which require correct line and ball flight. This is immediately apparent as the golfer stands on the 6th tee, a blind tee shot to a fairway falling away from and to the golfer's left. The 7th tee shot provides little respite as a series of fairway bunkers further compound the situation. The "up and over" blind tee shot on the 8th is perhaps the most difficult, especially when considering the approach shot. The 9th tee shot, while seemingly benign is a test of getting the correct club as far down the fairway as possible to allow for a level stance into the green.
Contrary to popular belief, the golf course is not simply "Fade the ball on the front and draw the ball on the back." Ample width is provided for the wily golfer to use both shapes to his advantage.
With all this in mind, the routing offers this progression of tee shot severity (This without the Par 3s).
Severe
Mild
Mild
Moderate
Severe
Severe
Moderate
Mild
Mild
Moderate
Mild
Moderate
Severe
Severe
That's a well-balance progression of 4 Moderates and 5 Milds and Severes. Not bad for Mr. Petty.
Greens
Gentleman, welcome to flavor country.
The greens at Huntingdon Valley can be enigmatic. Since the general trend of the terrain is into the bowl, it can be easy to both underestimate the break toward the creek, and overestimate the break toward the creek. Flynn's greens use some very subtle contours (especially apparent on the 3rd and 15th holes) that seemingly break uphill due to the overall slope of the green being masked by the subtle local contours.
The fact is, the greens at Huntingdon Valley could be one of the most educational studies in how the golf architect's craft can be used to hide the hand of man and beguile the mind of the golfer. Flynn's blending of man-made slopes into the hillsides on 2, 3, 6, 9, 10, 12, 15, 16 and 18 all serve to throw the golfer off as to what his contours will do the putt.