I definitely agree it's the best movie I've watched this year! When I was watching Iron Man I thought, wow, this is good stuff. But The Dark Knight just blows Iron Man out of the water!
The action sequences are definitely ace, especially that one where Batman flips over a [spoiler!] (OH MY F*#KING GOD!!!) and the huge car chase scene with the Batpod. Aaron Eckhart was much better than Tommy Lee Jones imho, much more realistic and human and he portrayed the breakdown of Harvey Dent really well.
Of course, props still go to the mindblowing performance of Heath Ledger. He's just so incredibly mesmerising! You quite literally can't take your eyes off him. Halfway through I realised I was shaking, and I thought it was the air-con at first until I realised I was scared shitless. He's simply awesome, unhinged and pyschotic.
Yeah, I ain't gonna spoil it anymore. Bottom line is: prepare 30 bucks, and watch it three times!