Sondheim's most underrated show?

I've always been obsessed with Sondheim's musicals. In general, however, my fascination is entangled with broad features of his technique and aesthetic vision, rather than with any particular work. In the former category, I love the clarity with which he discusses the details of his craft. He often stated in interviews and lectures that writers/composers should be able to defend every word of their librettos and every note of their scores, and this is an ideal he certainly pursued - and indeed, this self-awareness is something that unites all of the artists in my pantheon, especially Mozart. In the second category, I resonate particularly with the ambivalence so many of Sondheim's characters experience, as well as the philosophical acuity of his shows (something I wrote about at the end of last year). 

Nonetheless, even if my intellectual interest in Sondheim is bound up with aspects of his technique and vision that apply to all of his shows, I can't help but have developed favorites. These works, to which I return again and again, are, perhaps unsurprisingly, beloved in mainstream culture as well. I find Sweeney Todd to contain some of Sondheim's best musical storytelling; I find Sunday in the Park with George and Into the Woods to be his most philosophically stimulating and meaningful shows (even compared with the rest of his extremely meaningful output); and I love the musical classicism of A Little Night Music, the verbal brilliance of Follies, and the cleverness of Pacific Overtures. None of these choices is unusual; none cuts against the cultural grain.

But in the course of revisiting much of Sondheim's work over the past few months, I've started to wonder whether Merrily We Roll Along could be his most underrated work. It was commercially unsuccessful (though this isn't saying much, since by this standard most of his output is criminally underrated). But my impression is that Merrily is also underrated by many critics and musicians. I had certainly dismissed it for most of my life, as had many of my family and friends. I've never seen it performed live, nor have I seen a theatrical recording that seemed to do it justice. Thus, I can't speak to the overarching effect of the show as a piece of theater. However, from the point of view of the songs, it has some of the best and most impressive writing I've encountered in Sondheim's oeuvre. These are better than much of Follies and Pacific Overtures, and Night Music, at least, and I could imagine that the show as a whole might be better in some ways than Sweeney or Into the Woods.

Performances of three particularly good songs:

"Not a day goes by" (it's amazing how much Sondheim can do with a simple minor triad, not to mention the power of the text and the extraordinary performance):

"Opening doors" (one of Sondheim's epic puzzle songs, complete with a joke about Stravinsky in the middle, here sung by the original cast at the 20-year reunion - an easier rendition to follow than in their earlier studio recording):

"Our time":

The fact that Merrily strikes me as being underrated also raises the (related) question of whether some of his other shows are overrated. In general, I don't think that this is the case; Sondheim's work is so good that even now it's probably, on the whole, a bit underrated. (And I'd also guess that even many of his devotees don't realize just how great he was, and thus that he's in that sense underrated, even by those who do love his shows.) Nonetheless, I suspect that some other of his shows have received more attention than they deserve in comparison with Merrily. For instance, Pacific Overtures does have some nice moments, but its score isn't as consistently great as Merrily's; and Night Music has wonderful music, but the play is extremely shabby both in conception and especially in execution.