Oh, I totally agree! I'm a big fan of the Patrick O'Brien books and that's one of my favourite films of all time. Apparently there were plans for a sequel but they were put on hold because the film didn't do as well financially as the studio hoped and because of Peter Weir's other work. I think I read recently that it might still happen, though.
I always feel a little sad watching the movie, my dad was a big fan of the books and he would have loved the film but he died just before it came out.