Taken as a horror flick, the movie ain't half-bad, either.

Believe it or not, the U.S. market is pure gravy for the Mamma Mia! film, which is already at No. 1 in England, Australia and several European countries. Even so, the soundtrack album (which dropped on the 8th of July) is expected to enter the Billboard charts at No. 7: Pretty impressive for a CD of ABBA covers by movie stars of, shall we say, exceptionally varied levels of vocal accomplishment.

(Of course, many will find the notion of an all-ABBA musical fronted by AARP-eligible actors terminally uncool; those ranks will not include the curmudgeonly CityLife contributor seen blubbing quietly during Meryl Streep’s no-holds-barred rendition of “The Winner Takes It All.”)

Having given musical values somewhat short shrift in my review of the film, I feel duty-bound to make amends here. That’s a task complicated by the wholly inscrutable decision-making process that resulted in the album you see above. Sad to say, Benny & Bjorn have scored something of an “own-goal” by coming up with an original soundtrack that’s basically three-fourths of a loaf.

The play-to-film-to-CD process has left us with roughly five categories of songs: 1) Those that didn’t make it out of the stage show, period (”Under Attack”, “One of Us”, “Knowing Me, Knowing You”, “Thank You for the Music”); 2) Songs that have been added for the film (”When All Is Said and Done”); 3) Songs that are in the film but not on the album (”Chiquitita”, alternate versions of “Dancing Queen” and the title tune, “I Do, I Do, I Do, I Do, I Do”, and — heresy of heresies — “Waterloo”); 4) Songs that were cut from the film but are on the album (”The Name of the Game”); 5) Songs that were kept but re-purposed (”Our Last Summer” has been moved forward and made a quartet; “Take a Chance on Me” is moved backward and expanded, to become the formal finale; “Thank You for the Music” is cut from the show but turns up as end-credits music — and as an “Easter egg” on the CD, neither billed nor tracked separately).

Confusing, ain’t it? And why, with only 65 minutes of music on the soundtrack, weren’t at least “Waterloo” and “Chiquitita” accommodated? Seems there originally was to have been a two-CD “deluxe” soundtrack this autumn. But that’s been scrapped and we’re left with this shepherd’s pie. At least one gets to hear the full versions of songs that, in the film, get truncated by director Phyllida Lloyd’s conveyer-belt rush through the story. (I kept thinking “Already?”, as song after song made a premature appearance; one can sincerely say the movie is over too soon, though perhaps not in the best sense of the phrase.) For instance, having expanded “Take a Chance on Me” the movie then proceeds to lop off the latter half of this new, extended version — thereby depriving Christine Baranski of her solo lines and character resolution.

Between that and the CD’s omission of “Chiquitita”, Baranski’s performance — which benefits from being heard and not seen — suffers most. Her rich, Broadway-tested voice threatens to drown out her co-stars in their trios, and her turbo-powered rendition of “Does Your Mother Know?” nearly steals the album. By comparison, Julie Walters is an actress who can sing decently … which still puts her streets ahead of all her male costars, save juvenile lead Dominic Cooper.

Judging from Pierce Brosnan’s herniated tones, somebody should have confiscated his Springsteen collection prior to taping. Anglophone critics have tried to outdo each other in mechanical analogies for the indescribable sounds Brosnan emits (lawnmowers and outboard motors have been nominated). But words comparably fail to do justice to Colin Firth — whose nasal chirping could be mistaken for parody — and Stellan Skarsgård. At least within the context of the film, these gents’ old college try has a certain clunky charm. Preserved on CD, it will hearten aspiring karaoke vocalists everywhere. (”I couldn’t do any worse than that.”)

As in the movie, Amanda Seyfried combines ingenuous charm with a surprisingly assured and sumptuous singing voice. “Thank You for the Music” gets my nod for Least-Ingratiating ABBA song, but when Seyfried sings it to a simple piano accompaniment, what was fatuous humbug becomes touching and sincerely humble. A miracle!

But both the album and the film would fall like a failed soufflé were the central role entrusted to a singing actress one iota less talented or wholeheartedly committed than Meryl Streep. She finds just the right voice for each of her songs, whether it’s the Cabaret Lite attitude-throwing of “Money, Money, Money”, the silky warbling of “Super Trouper”, the title track’s Broadway belting or her full-throatedly operatic, caution-to-the-winds utterance of “The Winner Takes It All” (the CD offers her one-take studio rendition, while the film mixes it with phrases sung “live” as the cameras rolled).

As cathartic as the latter is, “Winner” packs even more of a wallop when heard and seen. It’s nothing less than one of the greatest musical-theatre performances in movie history. And whenever you think she’s giving everything she’s got, Streep reaches deep and gives you even more.

So, for all the reasons the soundtrack gives you to hold out in hope of something more comprehensive, the equation Streep + 8 ABBA songs = Game Over. Not having her interpretations of this rejuvenating music in one’s collection is an unthinkably bleak prospect.