I love this movie. Don't know how many times I've seen it, and there's always some new little bit of irony and/or innuendo. Fosse's concept for visuals is as acute as his choreography.
As much as I admire Hospital Hallucination #1, I think the montage at the very beginning of the movie is the perfectly expressed exposition of back story and all the events to follow.
It's also a great mashup of Lenny and Chicago, which I was lucky enough to see live on stage with Gwen Verdon, Chita Rivera, and Jerry Orbach. There are some great entertainers working today, but those were some hecka good ol' days.