The film so many fans of both series wanted to see after is first raised as a possibility in the late 90's and the highly anticipated film of the genre. And to be honest it did not disappoint me, I had my doubts on it working however it worked in so many ways. It covers the best parts of both series and has an interesting battle between Freddy and Jason and some interesting uses of their respective weapons and strengths.
They have an interesting story and you do not need to know the full history of either franchise to enjoy this film, it does help if you have an understanding of the mythology of the franchises. They still struggle to create characters outside the bad guys that you care about enough to not want them to die but it is part of the fun of both series.