I just saw it on Saturday night, and yes, it really is that good. Heath Ledger's performance is astounding, though I do suspect that some of his remarkable transformation may be due to chemical manipulation in addition to his undeniable talent. I mean, the guy died of an overdose not long after the movie was shot... But he really is stunning to watch.
The story itself is fascinating in its philosophical questions and implications, its musings on good and evil, and the nature of a hero, justice, and society. It's got plenty of eye candy and juicy action sequences, but it's also got plenty to keep the mind engaged on a deeper level.
Check it out.