There's a confusing naming situation - Heinlein's widow, Virginia, had the uncut manuscript published in 1991 as another edition. This is now referred to as the "original" version, (30 years after the version as first published!) Haven't yet read this edition - from what I hear, opinions are mixed as to which version is "better".
I've just reread the 1961 version, in a 1986 paperback edition I was somewhat surprised to find on my shelf - I probably bought it in '87 or thereabouts, and had more or less forgotten about it. (Frequently when I buy a book, it's after I've already read it - my wife thinks I'm weird this way.) I'll maybe take a look at the '91 edition (read? skim?) - not sure whether to look it up soon while this read is fresh, or wait a while.
I recently saw a slogan somewhere, to the effect: "The Silmarillion: For those who who think The Lord of the Rings is for wimps." I don't want to be snooty about it, but I kind of liked that!
Okay, I guess I should say more: 1) I read a highly-abridged "youth" version 'way back in grade school. 2) I started (at least twice) trying to read it in an edition my mother owned, but never got very far. That version was a rather thick paperbook, even though it was abridged! On finally re-reading "the real thing", I have to wonder if they abridged all the colour out of it - the author is incredibly discursive, but fascinating.
The book is a minor e-book milestone for me: the first book I've purchased electronically without having previously read it. I've been meaning to read the book for years: have looked for it periodically in my local public library, but apparently not so much as to put a hold on it. I've recently learned that is the first book of the now-complete "Wicked Years" cycle, wrapped up by the book Out of Oz, published less than two weeks ago as I write this. Interestingly, the last three of the four books were published three years apart each, while ten years lapsed between Wicked and the continuation of the series. At the moment I have mixed thoughts on the remainder of this series: one part of me seems to think that any follow-up books will be a letdown; and yet this is obviously a powerful writer. We shall see.
As a side note, I was reading this at the same time as Les Misérables - don't try this at home, kids, it can lead to some nasty whiplash ;)