I'd say about 70% of it is entirely enjoyable in a fashion akin to other Modernist literature. By the standards of contemporary YA and book-club lit fic, it's challenging, but by the standards of its own day, it is in many places written to be enjoyed. While it is true that there are aspects of it that are deeply overdetermined and a wealth of intentional allusion and linguistic play, that is for the most part frosting not presumed to be enjoyed by most readers—at least not in full. It is definitely true that Joyce assumed a classical education and a familiarity with e.g. the Odyssey (but also, the English canon itself such as it was in that day) that would be sufficient to allow many readers to appreciate his sardonic riffing.

For anyone who hasn't read it, it's worth saying, the first three chapters are considerably more abstruse and intimidating than the next half dozen or more, because they follow the consciousness of an anxious and precocious intellectual young man, preoccupied with Ideas, wandering through some awkward social moments and having overly intellectual reactions to them.

But then you switch to following a middle class businessman with a lot "earthier" of interests, and things clear up a lot.

The language can still be "challenging" in a way modern readers are not used to, but, it's meant to be enjoyed.

Much of it is actually best heard, as a lot of the "play" is in the sound of the language—there is a lot of pun and allusion in the way words sound like other words.

Later in the book the two principle characters meet up and go drinking in the sketchy part of town and things can intentionally surreal as they get inebriated, but, a couple of those later chapters are actually among the most straightforward to read.

All said it is however true that we're now well over 100 years distant from the world presented, so we increasingly need notes on things that were in no way meant to be obscure.

There are some excellent books around that serve as guidebooks, which can illuminate both those details and the allusions—and give you frank advice on which chapters you can skip through.

As to why one would read this, that is just one version of, why get a broad liberal arts education at all? The default answer remains as true or false as it ever was, it's because that is how you become familiar with the assumed fabric of our civilization, and become able to understand and participate in the discourse of today. There is no end of "issues" with the historic canon, but it remains the lingua franca of "serious high culture." If you don't have any familiarity with it does not mean you aren't living a full life; but it does mean that there is a sizable territory of shared public life that is closed to you, which might provide a rich set of tools for understanding issues that appear permanently part of the human condition.

Whatever else is true, the canons we have represent the collective curated coursework we have produced which recapitulates the intellectual underpinnings of contemporary society in most of its aspects, and provide historical perspective on the hows and whys of where we are. It is from this stuff that contemporary politics, science, religion, art, and moral reasoning emerged, for example. We are a lot more savvy now but all the deep serious mistakes and flaws of the classical canon—but it remains even in this, a common territory and a common point of reference.

Anyway, if you want to read just one bit? The "Sirens" chapter read aloud is amaze-balls.