Photographs by Joan Marcus/Courtesy of Spamalot; Illustration by Sean McCabe

Hilaire Belloc’s scrumptious Cautionary Verses say: “A Python I should not advise— / It needs a doctor for its eyes.” If only the producers of the frenetically hyped musical Spamalot, wobblingly based on the movie Monty Python and the Holy Grail, had received his advice. I would offer one more such suggestion: Call for not an ophthalmologist but a play doctor.

Too bad. When Monty Python’s Flying Circus was flying high, it reached comic altitudes of which only a few vestiges survive in Eric Idle’s book and lyrics, and John Du Prez and Idle’s songs. I guess one problem is that back then, a team of six Pythons was at work; on the musical, only one is left, and even his motor is idling. Another problem is that the musical describes itself as “lovingly ripped off” from the movie, when actually, like Macduff from his mother’s womb, it was untimely ripped, though not too soon so much as too late. The old jokes, unless you are a Python groupie, mostly show their senescence; the new ones, mostly their puerility.

Granted, all is not entirely lost. The show opens with a splendid set by Tim Hatley (the later ones are just as good), good and goofy costumes also by him, and several jolly ideas I must not divulge. For a while, some amusing things happen, with Mike Nichols’s helpful direction and, later, some nicely zany choreography by Casey Nicholaw. And there are some droll people onstage: Tim Curry, as King Arthur, though he will be reduced pretty much to a straight man; David Hyde Pierce, until his material becomes too gross and, worse, repetitious; and the one performer who will remain wonderfully above reproach throughout, the undauntable Michael McGrath as Arthur’s servant Patsy.

But, as an early number, “The Song That Goes Like This,” typifies, what starts out funny will soon drag. Galahad and the Lady of the Lake sing in duet: “I can’t believe there’s more / It’s far too long I’m sure / That’s the trouble with this song / For this is the song that is too long.” And it doesn’t even stop there. It is, of course, meant to spoof other shows, but the joke, like many others, boomerangs on Spamalot: What was once a fast-moving Python has become a sluggish boa constrictor, coiling itself around a gag unto suffocation.

I repeat, there are still things that work, such as the comic duel in which a knight gets sliced down to a torso, but still carries on, sort of; or certain projections that take us back to Terry Gilliam’s original visuals; or Hugh Vanstone’s lighting that keeps us surprised and tickled. But we the audience are not loose-jawed pythons who can swallow a young goat whole; we end up—by Act Two, if not sooner—with longueurs that stick in our craw.

There are even some casting problems. Hank Azaria, a usually good actor, does well by two of his parts; less well by two others. Sara Ramirez, as the Lady of the Lake, into which I’d rather have her go jump than emerge from, fails at everything: acting, singing, even looking right. And of all the jokes about seeking the Grail on Broadway, and about Broadway in general, only one is really funny, and it is milked to the point of 1 percent milk and 99 insalubrious fat. Eventually, the second act turns into an overextended Forbidden Broadway skit, much lengthier, unsnappier, and scenically overelaborate. Satirical spoofs want to be lean and mean; here, like that Very Expensive Forest that keeps reappearing as another and yet another part, the humor sinks from visual and aural obesity.

Now, if ever, is time to conclude with a lament for the current state of the Broadway musical. Where once there was true originality that takes chances, now we have nothing but previously tested stuff, as if success in another, earlier form, guaranteed safe transport. There are to my knowledge highly promising musicals by old, expert hands languishing in drawers, because the new, corporate producers will only sponsor supposedly surefire, farcical, or sentimental recyclings. Unfortunately, what may or may not be financially safe is artistically almost always a surefire disaster.