Adaptation: What's the Deal?

This comes up fairly frequently so I think it needs to be clarified.
Change is good. It's strange, it's harsh, and at the time you go.."I'm not sure about this", but more often than not it is for the better. If you look at some of the most faithful adaptations, they tend to be pretty boring. Sure if the original was good they are fantastic, but they end up feeling pretty boring. And the truly amazing and most beloved adaptations (The Dark Knight, Kick-Ass, Scott Pilgrim), go off from their source material to create something new, exciting and fresh.
This came up for me for 4 reasons. Number one, Walking Dead just ended and I'm pissed I didn't get the awesome ending from book 1. Pissed. But at the same time, I understand their reasoning and I can see that the changes may change my favorite characters but they add sucha new dynamic that I have no idea where the story is going to go. Number two someone being pissed that C.S. Lewis' "Masterpieces" (I know there is so much wrong with that statement) being changed to be a movie. Um, Duh? It would just end up Last Airbender all over again. Lost and lonely having been stripped of all character to maintain the plot. Number 3; Black Swan. A movie about a new interpretation of Swan Lake that is not only what they are doing as a Ballet but is also reflective of the plot of the movie. And lastly the new Buffy movie's existence.
Obviously the first and foremost question is does this movie work? If it doesn't, of course you are going to blame the writer and the film makers for screwing up your book. But they aren't. Most books inherently shouldn't be film. They are books. So to become film they need to be changed. The best translation I try to offer is that it's like trying to take Lord of the Rings and adapt it into poetry(but something with hard and fast rules like Iambic Pentameter). It isn't going to work out so well. Sure, some things are very visual and translate easily. The fights in Scott Pilgrim bam, take a very visual things and give it movement. So it has to be a good script or the movie will suck. Look at last Airbender. M night didn't understand why this show was so beloved wasn't the plot(though that wasn't bad either), and instead it was about the characters. So when he striped the characters of who they are and their idiosyncrasy, it starts to fall apart. We the audience would never have minded the plot changes they had made if they just made the characters work. If the characters work, and that is what it was all about(and let's be honest, most of the time that's all any of this is ever about), then the changes don't matter. It is about the feel and the emotion of it. A friend of mine asked me after I saw Flipped, how it was. Because she had read the book she knew that it was deeply rooted in emotion and that if it wasn't true to emotion it would never work. Luckily it did, and I'm told they took material out, added material, but it was still good.
Consider this Dexter fans, in the novels Dexter is driven to kill by some dark demi-god, but just because he's fucked up. And no it isn't Harry.
Speaking of Harry, I've spoken about the changes thus far, let's talk about when you are too faithful. These are your Harry Potter and the Deathly Hollows where in the event to prove to your fans that you can do it without changes results in two weaker films instead of one fantastic film. This should have been the best in the series and instead it's only half a movie. Lord of the Rings. Oh boy. it's a movie, 9 hours long, about walking. And in many ways the original animation adaptation is better(except that god awful Return of the King). It did what should have been done which was streamline it and still pay tribute to the rich deep world that was created.

So the places where these things go horribly wrong tend to be when you don't get the feel of the original right, or you get the feel right but you forget that its a movie your making, not a novel. I can't stop midway through a screening and flip backa few scenes now that I know this new info. A book and a movie are two inherently different things so changes must be made. Film is a very specific type of media. So if you take away anything, please take away the fact that they aren't the same. And a translation should never be exact.

One last note, adaptations should include change. It is giving the material to someone else to see how they do it. Its much like how in the world of Theater that your director can interpret the story and script in many different ways. He has the skeleton, and he fills in the meat and the flesh and the goey bits with actors and stages and lights and suggestive meanings. Myself and a large handful of other writers are of the mind that, "I've done this work already, let's see what this other person can do with my material". Sometimes it's better, sometimes it's worse. But often it is different. We don't change Peter Parker's origin, but we sometimes change Peter Parker and his life. Iron Man was born in the jungles of Vietnam, we updated him to be in the middle east. Don't assume that because it's different it'd be bad just because you love that original so much. The original isn't going any where. You still have it. It's still your baby. You can still breastfeed it 12 years later(I know, creepy ain't it?), the movie doesn't ruin it. And actually, a bad adaptation often gives your original a little more spotlight. So wait and see before you hate of something, and don't hate on it for change unless that change strips any thing that was good about it away.