You can't generalise.
Surely each screen adaptation has to be judged on it's own merit. Most of those I've seen have done reasonable justice to their forebears.

You have to consider the work taken in converting written word into watchable motion pictures. Personally, I really appreciate the talent and skill required to take that experience from 'the mind's eye' and actually sculpt it into something that looks good on screen, without a narrative to explain what it smells and 'feels' like. The main challenge being that of narrative and real-time.

I don't have the memory to quote specifics, but think of the way that narrative can interject a hectic fight or even battle scene to closely describe sweat glistening on throbbing biceps and the pungent scent of tribal jockstraps colliding. You have several hours and an unlimited amount of imagination to visualise scenes from a book, where a director may have to try and squeeze all of that detail into a couple of minutes or even a few seconds to fit time and budget constraints.

That said, there are plenty of productions that mercilessly butcher good original works by missing huge chnks of plot or just missing the point entirely. I have to say that the overall advantage is time. A good adaptation can convert a couple of days reading into a couple of hours. Everyone reads a book then watches the film and say's it wasn't as good. More people should try it the other way around. I've read a couple of books after enjoying the film and came away wondering why I bothered as the film did a pretty good job and it certainly wasn't worth the extra time spent on reading the book.

I for one would rather waste 2 hours watching a shit film than 2 days reading a shit book.
(Greencloud Wanted to go fishing on, Tue 20 May 2008, 15:24, Reply)