The success of “American Idol” and “Glee” has created a major market for collections of cover songs that would have been unthinkable even a decade ago.

For a long time, people (i.e. me) wondered why would anyone want the equivalent of karaoke versions (albeit very well-produced ones) of songs rather than the usually far superior original. A legion of “Gleeks” proved they do.

Therefore, there would seem to be a built-in audience for the soundtrack for “Rock Of Ages,” out today, June 5. which features the same executive music producer, Adam Anders, as "Glee."  The movie, adapted from the long-running Broadway musical, opens June 15.

If you’ve given much thought to how Tom Cruise would sound as an Axl Rose/Joe Elliott-type lead singer or if Alec Baldwin’s estimable talents extend to warbling (we’ll go ahead and tell you “no” on that one), this album gives you the answer.

As with most ventures of this sort, some tracks work better than others. Similar to the Broadway cast album, five of the tracks are mash-ups of two or more songs and the result can be a train wreck. Add up to six different actors/singers vying for space on the same song and it creates quite the pile-up, such as on Whitesnake’s “Here I Go Again,” which features five different singers trading lines.

We’ll get the obvious out of the way: any track that features Mary J. Blige, who plays strip club owner Justice, is a pretty safe bet given that she has more vocal chops than all the other singers put together. On a mash-up of “Shadows of the Night/Harden My Heart” she and Julianne Hough’s voices have a nice contrast: Hough’s voice, in general, is sweet and thin, and the way the duet plays out in the movie as they first meet works on record as well. Sadly, Blige has no songs of her own on here, but, then again, there’s no shortage of those in real life.

Diego Boneta, who plays the young male lead, Drew, is second to Blige in vocal talent.  He’s a strong singer who has already released two solo albums. His straight-up pop rock voice makes him a natural on both his tender tunes, such as “Waiting For a Girl Like You” with Hough or on thumping “I Wanna Rock.”

So how is Cruise? Better than anyone could have expected. As you probably know, he studied with Axl Rose’s vocal coach to learn to sing and while he never sounds like he’s totally comfortable (or looks it, in the movie), he does a fine job. His best numbers are the rockers, such as on, not surprisingly, “Paradise City,” since he’s mimicking Rose (which can’t be easy) and Def Leppard’s “Pour Some Sugar on Me,”  although he and Malin Akerman pull off a decent version of “I Want To Know What Love Is.” His absolute commitment is commendable.

There are a few missteps: Hough’s and Cruise’s take on the Scorpions’ “Rock You Like a Hurricane” is one of two cringeworthy moment. It’s an unfair fight to begin with: few could ever equal Klaus Meine’s full-throated vocals, but they have taken a dull knife to a gunfight.  Same with Catherine Zeta-Jones’ cover of Pat Benatar’s “Hit Me With Your Best Shot.” As she showed in “Chicago,” Zeta-Jones can sing, but her performance here is so mannered and awkward that it’s offputting.

The audience for the album  will be those who see the movie and the staunchest fans of each of the participating acts--anyone who’s that crazy about these ‘80s hits will want the originals. There’s not a likely single on here that radio would play, though, remember, that’s not unheard of: Huey Lewis and Gwyneth Paltrow had a No. 1 adult contemporary hit with their cover of Smokey Robinson’s “Cruisin” from “Duets” more than a decade ago.