Great question Ran!
Lehigh is a real sleeper--no doubt about it! I too have become super fascinated by the course in the last year or two.
Because Lehigh has not gotten the recognition it deserves in the rankings I guess it's natural that people would look for weaknesses in the course.
Maybe there are a few small weaknesses in Lehigh but I think it's important not to try to make the course into something it isn't and probably was never meant to be. I really don't think Lehigh is or was supposed to be a big full-blown championship golf course of the type of Shinnecock or even the complicated and unique architecture of Huntingdon Valley with it's demanding topogrophy and ever-present thin-margin danger making the latter a "championship" course in a scoring sense.
Lehigh, to me, is a really solid members' course, for probably every level of player period, and should be respected and ranked as such.
Lehigh is proof, again, that Flynn was probably the most clever and inventive course router in the history of the game! Flynn seem better able to "roll around" the sites of the projects he took on and deal with the topographical constraints architects' generally face, and make those constraints more interesting for golf than any other!
Flynn "butted into" hillsides and such more inventively for golf than any other architect I've ever seen. He designed holes as well as any other I've ever seen on sideslopes too! At least three holes on Lehigh use dropped elevations as well as any other architect! Flynn seems somehow to pull off radicalness without being too radical somehow. It might be instructive for us architecture addicts to remember and to truly understand that Flynn himself was a pretty "radical" guy (sort of a daredevil) and certainly that showed in his architectural expression!
As true as that may be to someone like me, it's extra interesting to observe the subtle and simple architectural brilliance of some of his other holes at Lehigh. For vastly differing reasons I would put these holes into that subtly brilliant category with exclamation marks; #1!, #2!!, #5!!!, #10!!!!, #15!!!! Most of the others holes have already spoken for themselves in their drama and uniqueness (not subtle)!
Other than his "rolling around on the site" routing brilliance just mentioned, I personally, give his routing style a thumbs up for its variety and balance and the uniqueness of his "outside/inside" routing style in such evidence at Lehigh and certainly Huntingdon Valley and to a large degree Manufacturers and Lancaster too!
As most people notice, and Pat Mucci mentioned, the seemingly inconvenient walk from #1 green to #2 tee may be a bit of an architectural glitch. But is it? Not really! It is Flynn's one-time technique (if you think carefully about Lehigh's routing) of getting the entire front nine outside the entire back nine!!
But if you ask me what Lehigh's weaknesses are, I would say its par 5s! But probably not for the reasons you would think. It's important to note that Lehigh is a par 70 and its two par 5s are short "go/no go" par 5s, and very good ones! Most of the truly difficult (to score on) par 70s have par 5s (generally two) where it's not easy to make a par (ex. Pine Vally and Merion).
As Mark Fine said, in answer to my questions about Lehigh's two par 5s, that if you try to gamble with either too much you might run into trouble, but I really do maintain that if you don't try to gamble on these two par 5s they are basically two very simple holes to make par on! That to me in the only weakness the course has--but in the broad scheme of things (all the other varied and good holes) probaby a very small weakness at that!
To answer some other remarks on this thread, I also think that the look of the grass bunkering on #11 is dynamite! It gives the green complex from the fairway way above it a "shadowy" and undefined look which is wholly unique. The grass grass bunkering is also highly functional, particularly when you consider the river-side site of #11 green.
The two par 5s may be small points and probaby shouldn't really be considered weaknesses, unless you are thinking of some touring pro who would likely make mince meat out of the course. But, so what?