There's an obscure 1994 book by Clyde Haupt that discusses film and
video adaptations of Huckleberry Finn.  It is reviewed (by me) on the
Mark Twain Forum web site. It's a frustrating book, but it does include
a lot of information about the various adaptations.
  It's certainly true that no adaptation of HF is worthy of the book.
Once you get beyond that, however, there's a lot of interest in
examining these adaptations for what they tell us about the culture that
created them, as well as for discussing why Mark Twain's HF is great and
"Mark Twain's Huckleberry Finn" usually isn't.

Glen Johnson