Few can claim to know what Michael Jackson was really like, but the King of Pop's new film This Is It attempts to give the world an insight. The documentary goes behind the scenes of his London comeback concerts at the O2. 100 hours of rehearsal footage have been pieced together for the feature. In it, the legendary musician appears as a perfectionist, calling out directions to those around him to "feel" the music and "let it simmer". Despite worries from fans that he was working too hard and was struggling with his health in his final days, the 50-year-old appears to be in his element while dancing energetically to routines from hits like Bad, Smooth Criminal and even some numbers from his time in the Jackson 5. Michael's 50-date concerts in London were billed as the most expensive and technically advanced live shows ever. As well as aerial artists and pyrotechnics, the staging included sequences filmed on green screen beforehand and 3D special effects. The 112-minute documentary offers an entertaining and at times witty portrait of Michael Jackson, showcasing what he'll undoubtedly be remembered for, his music. This Is It is released on October 28 and will be screened in cinemas around the world for just two weeks.