When I did it, i was able to lift an edge and get most of it off in one sheet. After that, the best way to get the excess glue off was with a razor blade and then a clean up with metho afterwards. The razor blade wont scratch your window and hopefully you don't need to do the rear with the demister. It is time consuming, but it came up a treat. I'm not sure if anyone has any better ideas.
Cheers
Tim