Having never read the Harry Potter books, I don't have a good basis to determine if it was accurate to them. But as far as a moviegoing experience, I found the movie slow-paced and chockfull of those 'extraneous things that seem irrelevant at the time of introduction, but will become earth-shatteringly important at a later date'. The movie had decent acting, and the effects were as good as the previous movies in the saga. For completeness, I'd recommend seeing this movie. But, make sure you got good rest before seeing it as it will be boring at times.
I thought it was very good, and Heath did a very cool Joker. However, I think that there was too much hype associated around his 'potential' Oscar-winning performace. The Joker was sinister, and brilliantly cunning in his overarching plan to (further) ruin Gotham & her defenders of justice. Heath played the part of a manaical sadistic sociopath very well. Christian Bale was super as the Batman. The other actors did a good job in showing the 'human' element that comicbook heroes/villains always seem to trample on/over. Some people complained in my theater about the length of the film. I thought it was just right to show the true scope of the Joker's plans ; if it was shorter, it would have seemed rushed. So overall a very good movie, but all the hype around Heath Ledger, for me, made it seem a bit of a let down that I wasn't _completely_ blown away by his performance. 4.25 out of 5 stars from me.