The Silmarillion, in what is a frustrating yet accurate mirror of real world mythologies, is the sort of thing that is best read when you already know the stories and yet you become familiar with the stories by reading
The Silmarillion. My first read-through is now so far behind me that I don't remember it, beyond a general sense of lostness/bewilderment mixed with trying to keep all the Fin-s straight (not the Finns--that's a strictly on-this-website problem
).
The second time through, which I hardly remember any better (it's been over twenty years for both those early read-throughs), I
do distinctly remember having recourse to the family trees at the end, and I definitely spent more time keeping track of the relationships and the names of the Valar and the divisions of the Eldar, etc.
It is definitely a book the rewards rereading. I find now, after the aforementioned twenty-plus years, that, in some moods, I even prefer it to
The Lord of the Rings. But it isn't as accessible as the LotR--and there are some who just can't get into that. And there's nothing
wrong with not getting into them, one or both. But the Silm is very much the key to the rest--to the History of Middle-earth Series, that is, because other than an LotR-sized digression in the middle, the HoME is the history of what becomes the Silmarillion, and if you don't know and love the Silm, you'll be lost in the references and have no reason for plodding through.
But, of course, to speak of the HoME is to
really speak of things that are not to everyone's tastes.