Actually I saw that in 1989's Batman and accepted the "style" of those films at that point. Carrey played the role within the style that had been set for those movies. They weren't the greatest, but they were enjoyable.
The Dark Knight feel can be lightened a bit without turning the series into camp or destroying/corrupting what Nolan is setting out to do with the films. The next villain should not try and top the Joker, and instead just focus on the new characters for that film.