Surprisingly, the only scene in the movie that came across as overcomplicated (for me, anyway) was the first big action sequence. It's the only scene in the film where the audience is forced to focus on too many things. We're supposed to focus on Schreck because of his speech. But we're also supposed to focus on Selina because she forgot his speech notes. But we're also supposed to focus on the Penguin (who we haven't seen yet at this point). But then the speech gets hijacked by the Red Triangle Gang, so we have to focus on that, too. And now because of the gang, we have to be introduced to Batman too. So now we have to focus on Batman. That's a lot of stuff for the audience to focus on in the first 10 minutes of the movie, and I think if that scene were re-edited to have a clearer focus, it would fix a lot of wrongs with the rest of the movie. The constant back-and-forth editing of that scene didn't help either.
With that said, though. I agree on Catwoman. The more uncut her performance is, the better.
It's funny that what bothers you about Batman Returns is the humor and campiness, because this was the movie that got both Tim Burton and McDonald's into a lot of trouble with families who were upset over how excessively dark this movie was for their kids (and who shouldn't be watching PG-13 movies, but that's my opinion). This was one of the big reasons Joel Schumacher was hired to replace Tim Burton for the later Batman films, so that Batman could be targeted to a more family-friendly audience. And we all know the rest of the horror story that resulted from that.
Sure, we're free to laugh however we want to, but back then, those first two Burton-directed Batman movies were hardcore for their time, and not just because Catwoman dressed in that grungy leather outfit. Most people were not familiar with the comics at the time, and only knew the Adam West TV series, where the most evil thing about Burgess Meredith's Penguin was his overuse of quacking noises. So, it's no surprise that Danny DeVito's Penguin came across as quite a shock. I also thought the Penguin's plan at the end was more disturbing than cartoonish. Especially with the whole killing of the firstborn part of the plan which springs to mind a lot of dark biblical comparisons from the book of Exodus.