Well I think his point is this. If it had more embraced the fun of its origins it would have been better.
Its origins are dark.
Given how deathly seriously the movie takes itself though it hardly can escape on the fun defense. I like the Burton Batman's better precisely for that reason.The Dark Knight
is too grim, too self-serious, and does have a weak third act (although the Two Face stuff is the best part of the movie).
What do you think are the most glaring plot holes?
Just the way people behave so stupidly in the movie if they aren't the Joker. The car chase scene itself is gigantically implausible. Even more so is smuggling enough explosives into a packed hospital to blow it up and smuggling explosives onto ferry's when you've got the whole city on lockdown. The Two Face stuff is the best part which is why it's a total shame that the ending both rushed that and didn't put it in another movie and simultaneously managed to drag on and be rather dull.
I should clarify when I say fun it should have embraced the inherent underlying current that Burton managed to tap into. That's what the Batman Animated Series did really well too.