Schindler's List was very good, it does cut out alot of Schindler's life before and after the war, so you don't get as true an impression of the man Oskar Schindler but maybe it works better as a film (certainly a 'blockbuster') for it.
I haven't read
The Princess Bride but I'm sure its been mentioned before that its very true to the book?
I thought the Harry Potter books did very well at capturing the feel of the books and
The Andromeda Strain is a really great translation of a Michael Crichton book,
Sphere isn't.
High Fidelity, proof that occasionally a good adaption can even survive being transplanted (England to America)
I wasn't actually a big fan of the movie to start with and having now read the book I like
Contact even less and finally, I am still waiting for that really good adaption of
Dune, unfortunately it looks like they're going to keep trying untill I get it
.