One sentence that jumped out at me was when Joyce parallels each event in the day to a religious event (the service of St. John, simchat torah, etc). I think this is so interesting, because it shows that the Odyssey parallels are far from the only lens through which to view Ulysses, and Joyce is here lending his imprimatur to those other lenses. I think that some analyses focus too much on the parallels to the Odyssey, and those are really only a framework on which Joyce was building this novel. (He also had an organ, a color, and an art form for each section, but we rarely find in-depth discussions of those).
I would argue that, although those parallels are interesting, there's so much more going on that you can miss the forest for the trees by focusing on this one aspect of the novel's scaffolding.
As to the actual substance of the episode; it's probably the densest episode in the book. We can deduce Stephen and Bloom's ages, the size of Bloom's muscles, the books in his bookshelf, and so on. It's almost a case study in throwing so much information at readers that relevant details are subsumed. For example, Molly has not even tried to hide her dalliance with Boylan, leaving his cigarette stubs out in plain view for Bloom. This is tremendously important (does she despise Bloom? is she hoping to get a rise out of him?), but it's given as much emphasis as how old Bloom would be in the year 1933.
And Kenner points out that even in all these details, the items left out are important. When Bloom tallies up his budget for the day, he leaves out Bella Cohen.
This section also shows Stephen at his worst, I think. When he and Bloom trade songs, Bloom sings "Hatikva," while Stephen sings an anti-semitic song. At best Stephen is deliberately obtuse, not realizing that the song would hurt Bloom's feelings. At worst, Stephen wants to upset Bloom.