The first half of the story is dedicated primarily to Mr Negative and the demons rising to power after Fisk is locked up, which I liked. As someone who isn't familiar with Mr Negative, I thought he was very interesting here. The second half of the story however, is comparatively rushed and overstuffed with undeveloped plot points. The Sinister six come and go so quickly, and accomplish nothing. Mr Negative got more screen time than the rest of the six put together. They felt like cardboard cut outs that were thrown in last minute for fan service.
Otto infecting the city with devil's breath came out of nowhere, and was completely out of character. Why did he do it? To make Norman Osborn look bad? The only excuse is that the arms made him do it, because until this point there was nothing to indicate he would murder millions of people at random.
What purpose did this biological attack serve in the story? At this point, the city was already in chaos, filled with escaped prisoners and Sable agents. Did we really need a plague on top of that? A city wide plague should have huge consequences on the story, but the plague has no noticeable effect on anyone or anything except Aunt May.
Essentially, the entire city was exposed to a plague solely for the purpose of killing Aunt May. What could have been a significant plot point was wasted, and now it can't be used in the future.
I understand many people don't agree with me here, but the death of Aunt May was cheap and undeserved. I've been known to tear up during movies, but this death didn't illicit any reaction in me what so ever. It was a disservice to the character, and it only served to add drama to an otherwise underwhelming finale.