This happens all the time, but I've never understood it. Why do people trash the plot of a movie that was based on a book? If you have an issue with the plot, it isn't the fault of the film, but the source material.
With a book of questionable literary value gets adapted to the screen, it can still become a very good film. Take
The Godfather, for instance. As a book, it's a fairly unremarkable genre exercise; as a film, the script takes liberties with some of the events and characters, and the visual template that Coppola gives to it elevates it from mere pulp to high art. With
Bridget Jones: The Edge of Reason (and
unlike Bridget Jones's Diary), the writers and director manages to gut the book - which is actually quite good - completely of what made it entertaining, selecting only the drabbest bits and then getting the cast and crew to make as drab a film as possible out of them.
So... yeah. I really really really dislike it when people say "It's the book's fault if a film is bad." For a really amazing film out of a not-so-great book: see
Psycho or
Adaptation. For a terrible film out of a good book, see most of the versions of
A Christmas Carol (except the Muppet one) and
Bridget Jones: The Edge of Reason.
To deal with everything else: I like Jane Austen novels but I can understand why people don't; the
Harry Potter series is very much in the realm of 'okay'; can't comment on
Buffy having only seen half of one episode; Tarantino is a self-diagnosed thief, but I wouldn't go as far as saying he's a 'hack'; LOTR: first one's good, second one's forgettable, third one NEVER ENDS; OMG yes Johnny Depp HAS forgotten how to act for most of the last decade; meow, Andrew, you have the claws out today!; that mention of
White Chicks had better be one of 'OMG I sooooo totally hate
White Chicks' or GTFO of my forum; and while I don't think Inception 'sucks', I do think it is very overrated.
Phew! Any more entertainment sacred cows we want to turn into sacred beefburgers?