Sgt. Pepper's Lonely Hearts Club Band is referred to as a jukebox musical. I would refer to it as a rock opera, which is narrated by George Burns and stars Peter Frampton and The Bee Gees. The Beatles' albums Sgt. Pepper's and Abbey Road provide the majority of the songs for the plot. It seems the original Sgt. Pepper's Band instruments are stolen by some bad guys and they must be returned to Heartland or the town's magic will disappear.
Peter Frampton and The Bee Gees (Barry, Robin, and Maurice Gibb) perform the majority of the songs in Sgt. Pepper's Lonely Hearts Club Band, but the movie also features performances by Aerosmith, Billy Preston, Alice Cooper, and Earth, Wind & Fire. The end finale, which sort of recreates the album cover, has a host of musical stars along with TV and movie personalities. There are way too many artists in that final scene to list, but if you're interested, you can find a list at this wikipedia page under Special Guests.
I had heard Sgt. Pepper's Lonely Hearts Club Band was a disaster of a film. I really couldn't figure out why it had gotten such bad reviews (other than people seemed to hate The Bee Gees essentially playing The Beatles). The movie seemed like a pretty innocuous musical based on the songs of The Beatles. At about the half-way point of the movie (somewhere near the disaster of Steve Martin singing "Maxwell's Silver Hammer"), I finally understood why the film doesn't get much love from people or critics....it became BORING, there just wasn't a strong enough storyline to propel the movie forward to the end. The only two saving graces in the second half of the film were Billy Preston's performance and the finale as discussed above. I guess the movie is worth checking out (something few did on its initial release), but I would recommend watching it in parts instead of trying to sit through the whole film at one time.