Do what must be done. Show no mercy.

I will preamble with this caveat.... Spoilers Ahead!
That said...

Anakin was sired by a Sith lord. Interesting. The Sith brought him into being to serve one purpose: destroy the Jedi.
He's got a dual purpose. On the one hand, for the Jedi, he fulfills a prophecy. The Chosen One, who will destroy the Sith and bring balance to the Force. I gather the prophecy didn't bother to get into specifics regarding just how we would accomplish this.
On the other hand, he was created to destroy the Jedi and usher in the return of Sith rule.
Of course, Anakin managed to very nicely fulfill both these chores.
The moment he drops his lightsaber and surrenders to the dark side, he understands his purpose. Why he is the way he is. He accepts it. Not with relish, but with resignation. And so begin an unfortunate chain of events.
I don't think the Sith planned on him having children. They wanted him raised as a Jedi, so the possibility must have seen remote at best. Not something to worry about.
And there was their undoing. I'm sure they scoffed at the Jedi prophecy. Little did they realize that because those children came to be, Anakin did indeed bring balance to the Force, and would find the compassion and selflessness within him to destroy the Sith. Destroy his master, and himself.
Good job, Mr. Lucas. Once again, the movie itself matters less than the story it tells. Star Wars remains greater than the sum of it's part.
Say what you will about directing, execution, wooden acting or stilted dialog. It's the story.
And the story kicks ass.

On a different note, there's tons of new armor! All kinds of variations. I swear Lucas does this to screw with the 501st. He's very tolerant, and indulgent, of our costuming group. We're a great group of people, and I'm proud to be a member of Vader's Fist. But, we have a lot of hard core fanboys. SW seems to have that effect on people. There are a lot of arguments over canon and screen accurate costumes. As with any activity that demands a lot of money and devotion, people tend to take it very seriously.
So here's Lucas, making it harder and harder to have hard line rules and stances on what is and what isn't "canon". Harder to make or own all the variations. He's having a little fun.
Hey... Kenobi said it best.
"Only Sith deal in absolutes."