The estate of Jimi Hendrix refused to loan the music rights to the film for André Benjamin to perform as Hendrix. The estate stated that they would not grant the rights unless they were allowed full participation in the film's production.
André Benjamin is actually a mediocre guitar player. In an interview with NME he said: "One of the hardest parts [was] I'm a right-hand guitar player. I'm a horrible right-hand guitar player. I wouldn't even call myself a guitar player; I just pick it up and fiddle with it every now and then. When it came time to do the left-hand thing, it's almost like walking backwards and making walking backwards look normal."
The Hendrix Estate did not allow any of his songs to be used, so he is seen performing only covers in the film. Infact, at the time the movie takes place (1966-67), Hendrix had three top 10 singles in the UK ("Hey Joe," "Purple Haze" and "The Wind Cries Mary") and a hit album ("Are You Experienced").
The trivia item below may give away important plot points.
There is a part when its shown that Hendrix "humiliated" Eric Clapton during a Cream concert. The scene, based on real events, shows how Jimi requests to jam with Clapton, and actually Jimi played the blues 'Killing Floor', leaving Clapton shocked with his talent. Ginger Baker later said in an interview about that particular story: "When I met Eric, I knew he was a great guitar player, but when I met Hendrix, I knew he was like a force of nature..."