Frustration with Ulysses.
I've gone from understanding only about 10% of Ulysses to hardly any at all. After looking at a SparkNotes analysis, Joyce apparently is experimenting with different narrative styles as the book progresses (starting around chapter 9). They're not kidding. I was seriously lost for many sections and only now that it's come back to a more usual style do I have any chance at all.

My limited observations:

• Joyce loves to pun and play with the language a lot especially through the voice of Stephen Dedalus. This is why I think of him as a Robin Williams of sorts.
  
• Ulysses is apallingly crude - mostly through the actions, obsessions, and interactions of Leopold Bloom. I don't mind explcitness, but this is just so coarse in places. Of course those would be the parts I understand. :)

It's funny I was looking at the SparkNotes analysis and they seem to think that Bloom is the more well rounded and sympathetic character, but he seems to me to just be sex obsessed. Dedalus, on the other hand, is funny though I'm sure he holds people at a distance with that humor also.

I'm on Volume 2 of 3 and am nearly finished with Vol 2 and Vol 3 isn't nearly that big, but I don't think I'm going to continue. I love Joyce (I liked Dubliners), but I think I'd get more out of his other works.

Refs:
http://web.nwe.ufl.edu/~kershner/bioe.html
http://www.sparknotes.com/lit/ulysses/