Reddit reviews The New Bloomsday Book: A Guide Through Ulysses

The New Bloomsday Book is a fantastic guide. I'm not going to say, "Don't be afraid of ULYSSES" because it is daunting. but for all its intimidation, its very fun. Imagine the language that you loved about Portrait except way more playful, lyrical, and funny.

"I've put in so many enigmas and puzzles that it will keep the professors busy for centuries arguing over what I meant, and that's the only way of insuring one's immortality." - James Joyce on Ulysses

This was essentially James Joyce's goal... and that's why Ulysses is my favorite novel. I would recommend reading A Portrait of the Artist as a Young Man first, and to get some guidebooks for Ulysses (specifically this one and this one)