For those moaning about Jackson, who would you rather have? Roland CGI Emmerich? James 3D Cameron?
Jackson loved the books and spent a long time getting the screenplay together. Not all elements from a book can be transferred onto the big screen, as it's a different medium and requires some skill to do this. Not everyone was going to like it, but despite the changes, it worked very well, and beautifully shot.
Hence a good reason why the film never materialised in the 50 preceding years since the book was published.