I'll be honest I skipped through most of the sewer (As I did for a large amount of jumps that weren't the fun slide parts). I would say the most difficult segments were any segment that involved jumping from more than 1 isolated cylinder pipe in a row. I wouldn't mind if those pipes were +%50 wider.
Maybe I'm too impatient and just wanted to get served content without working.
But the sewer section would be my vote for shit city