Some particular highlights: I love the Scylla and Charybdis scene in the National Library, partly because I have spent time there myself, and I've also handled letters from Richard Best (who famously told the BBC years later that he was a real person, not a character in some dirty book). I had forgotten how brutal the depiction of the Citizen in the Cyclops episode is, especially bearing in mind that the basis of the character is Michael Cusack. And I'd forgotten how lyrical and sexy Molly Bloom's soliloquy is at the end (I guess when I was reading it the first time I had been on a train all night, and had stopped concentrating). On the other hand, I found the Wandering Rocks and Sirens episodes boring and confusing, and the Oxen of the Sun episode doesn't quite deliver (ho, ho) on its promise.
My doctoral thesis was on Irish scientists of the 1890-1930 period, which of course Ulysses fits into very nicely. I was struck by just how often astronomy and astronomers are invoked - Sir Robert Ball, who I once wrote an essay about, actually appears in person in a dream sequence, and his books are mentioned several times, as is his successor in Dunsink, Charles J Joly. (I have even been invoked by Joyce scholars.) I don't think Joyce is making any grand points about literature and science; it's just that astronomy was an important part of popular culture, then as now.
It's also interesting just how long a shadow the May 1882 Phoenix Park murders cast over the story. Joyce would have been three months old at the time, and can therefore have had no personal memory of the events, but I guess for the generation who grew up in Ireland between then and 1916 it was their JFK moment - complete with conspiracy theories, and with the extra thrill of surviving, identifiable, well-known accomplices to the assassination.
Anyway, I shall probably read it again, and maybe I won't leave it another quarter of a century to do so.
A few weeks ago I was in Zürich, and I made the pilgrimage up the hill to the cemetery beside the zoo, where Joyce rests for eternity, and in a nice bit of reflexivity, can be seen casting a glance on his own grave as a thought strikes him while reading.
There are worse fates.