I'm a big fan of both books and film, but I think the films actually did a better job with Aragorn and Boromir than the books. In the books, Aragorn is a bit high-and-mighty sometimes, declaring I'm the heir of so-and-so and here's my mighty sword, blah, blah, blah. The books shows him as a more modest, quiet character who grows into his role over time, which just feels more natural. Likewise with Boromir. Consider the Council of Elrond in book vs. film. In the book, they introduce Aragorn as the heir of Isildur and Boromir pretty much takes it in his stride. In the film, Boromir is more clearly Denethor's son, saying 'Gondor has no king; Gondor needs no king.' A very effective line that sets up the tension between he and Aragorn and makes their reconciliation at Boromir's death all the more effective. Not a big beef with the book, but just an instance where I though the films really did a good job making the characters seem human.