Ive read the books and see the films many times and would never go as far as saying someone wont like it. Go into the films with the understanding that they had to change things due the constraints of the media. Things had to be cut, rearranged and changed to make them fit in 9ish hours of film.

For example, Helms Deep and the battle fought there in the book barely a chapter and change, the film adaptation I would argue is the best fantasy battle scene ever made.

Translating between medias is an art, not a science and it should be regarded as art and judged on its own merrits, along side its merrits as an adaptation.