Michael Jackson’s farewell film, “Is This It,” clearly meant to be a nostalgic, sentimental look back at the departed musical legend, is in fact a deeply creepy and disturbing exercise, in which we’re exposed to footage that was likely never meant to see the light of day, featuring a performer who at the time was, literally, days away from death.

There’s a whole lot very, very wrong here, whether it’s the movie’s naked, exploitative cash grab, its tedious look at the rehearsal process, or the fact that it’s using very imperfect, raw and unfinished footage of Jackson, who is described in the film as an obsessive perfectionist when it comes to his performances.

Probably the first concert film ever comprised entirely of rehearsal footage, “This Is It” was assembled from film taken of “The King of Pop” preparing for his scheduled run of 50 shows at London’s O2 Arena, which was, of course, called off after Jackson’s death in June. We get a look at Jackson’s creative process, as he tussles with director Kenny Ortega and his musicians and choreographers over every last detail of the show.

“This Is It” was assembled from hundreds of hours of footage by Ortega, who directed the “High School Musical” series and was also directing the stage show. He does what he can with the material, but you can’t help but think that had Jackson lived, this documentary either never would’ve never been released, or perhaps broadcast been as a minor VH1 special or something.

Jackson, throughout the film, looks ghoulish, rail-thin and generally sickly, and sounds like a nut every time he opens his mouth. His singing voice is less than stellar, and it’s clear, especially in hindsight, that we’re looking at a man who’s unhealthy, to say the least. That on its own makes it very hard to enjoy the film, much as one may love Jackson’s music (and I certainly do).

The other aspect of the film is a series of background videos that were to be part of the concerts, including an elaborate 1930s gangster tableau (to go with “Smooth Criminal”) and a 3-D, CGI-based remake of the “Thriller” video (I didn’t think anything was wrong with the original). These videos were practically a movie production in and of themselves, likely costing in the tens of millions of dollars, and gives us another clue why this movie was made — otherwise, all that footage would’ve gone to waste.

The stage show itself looks like a bombastic, overblown, multimedia debacle, of which music only plays a small part. Worst of all is a laughably heavy-handed section in which Jackson precedes “Earth Song” with an unintentionally hilarious poem about the rain forests, as a mini-movie plays of a little girl, threatened while playing in the actual rain forest, until an actual bulldozer appears on stage with Jackson. Jackson’s voiceover in this sequence sounds not unlike the parody of him on “South Park.”

There are a lot of interesting things about Jackson’s fascinating, only-in-America life — if you watched the news in June or July, you probably heard about them all — but the film delves into just about none of them. There aren’t any candid interviews, and we learn exactly zero about the performer that we didn’t know already.

Overall, the film shares a problem with those “Beatles Anthology” collections that were released in the mid-’90s, where we hear great, classic songs, repeatedly interrupted so the performers can discuss musical cues and the like. I fail to see the appeal in this sort of thing; how can they possibly improve on the recordings themselves? The only truly special moment in “This Is It” is Jackson’s performance of “Billie Jean” near the end, because it leaves out the GGI background video and 20 background dancers and everything else that mars that rest of the movie — it’s just Jackson, singing and dancing the way he used to.

Because Jackson has become much more popular dead than he was in his last 15 years alive, “This Is It” is sure to be a huge hit. But some filmgoers may find themselves asking, “Is this it?”