I keep thinking about what we owe, and what we don't, and I don't have a good answer yet. The other Clockworkers' posts strike me as well-reasoned. But I will say this, since Matt brought her up: JK Rowling may have kept some of her promises, but she broke a big one--that her plots would make a lick of sense. Instead, they make less sense the longer you think about them.
Voldemort: Here's the plan, Barty. You disguise yourself as Mad-Eye Moody for nine months, then sneak Harry's name into the goblet of fire, and then rig the contest in such a way that Harry is guaranteed to win.
Barty Crouch: What?
Voldemort: You see, the trophy is really a portkey! Ha ha! It will transport Harry outside the school, where my minions can subdue him and then use his blood to ensure the final phase of my resurrection.
Barty: Okay, but...
Voldemort: You dare to question me?!
Barty: Why don't I just, you know, hand him the portkey?
Voldemort: [Stares blankly]
Barty: I just walk up to him, hand it to him, and poof, he's teleported out of the school. We can do it tomorrow.
Voldemort: Barty. Barty. I'll overlook this because you're new. But you obviously have no idea how to be the FRICKIN' LORD OF DARKNESS, okay? That's MY job. Now drink the frickin' polyjuice potion, and I'll get back to you in June.
Now, this kind of sloppiness is not uncommon. How many breakneck adventures have your read, how many X-Files or Heroes episodes have you seen, how many comics have you inhaled that you enjoyed in the moment, but about 30 seconds after putting down the book or turning off the TV, you thought, Wait a minute...
Rowling particularly annoys me. Not just because her stories depend on some kind of attention-deficit disorder dream logic, but because she has sold so many books, and made so many children happy (including my own, and soon Matt's, I'm sure) that it's clear her readers don't care about the plot. They forgive her, or they don't notice, because they like hanging out with Harry for 800 pages. Which goes to show you: charm and wonder trump craft every time. Now: Would anyone like to discuss A.E. Van Vogt? Or the second drafts that PK Dick never wrote? No?