The movies aren't inconsistent in any way. A few minor things get changed for simplicity's sake, but not out-and-out inconsistencies. That's one of the great things about them. But if you're a reader of the novels as we are in this house, you'll find yourself watching the movies and saying "why did they take [x] out of it?" This is more a problem since Christopher Columbus left. He may not have the eye for stunning filmmaking that Alfonso brought (or that Newell continued) but he was at least slavishly faithful to the books, which I found to be a refreshing change for the film industry.

Once movie seven comes out, you definitely should read the books though. So many great subplots that may not matter but certainly are fun.