I just removed mine about one month ago. I used the heat of the morning sun (at Myrtle Beach) to warm the film. I used plastic razor blades to start an edge, then pulled firmly on the film at an angle to remove it. It tears at times but I was able to pull off some fairly large pieces. Not sure that will work with film that has really gone bad and cracked into many pieces.
Once the film is removed, I used mineral spirits to soften the glue, scraped off as much as I could with the plastic razor blades (had to do the mineral spirits and scraping two or three times in spots), then did the final clean up with a rag and lacquer thinner. I tried Goo Gone and Goof Off and neither of them worked as well as the mineral spirits/lacquer thinner combination. I also checked with a friend who runs an auto body shop and he said the mineral spirits and lacquer thinner would work as well as the other commercial adhesive removers, including the 3M stuff.
I was lucky and my paint was pristine under the film. I used some Meguairs cleaner/wax on the paint and it looks like new.