Lord Foul's Bane, the first of Stephen Donaldson's Thomas Covenant series, predates the 1980s fantasy boom. It would probably have been very easy for Donaldson to knock out a hackneyed Tolkien rip-off like later authors would.
But he didn't. Ignore those reviewers on this site who think that the plot is a Tolkien rip-off; it isn't. It's a fantasy setting, there's a quest, there's a ring. That's about it in terms of common themes. Tolkien wanted to create myths; Donaldson is trying something altogether more literary in the fantasy genre.
I say "trying" because arguably he didn't succeed. Literary critics I think were put off by the fantasy setting. Fantasy readers were often put off by the lead character and the "strangled prose" (more on that below). Thomas Covenant is often described as an anti-hero, but that puts him in the same category as say Elric or Blake's 7's Avon. Covenant isn't a badass sociopath like those two; sociopath yes (but with good reason - 20th century society has turned on him out of prejudice because of his leprosy), but he's too self-pitying (massively so), cowardly, useless, whinging and snivelly to be badass. He is not remotely aspirational as a character, so he's neither hero nor antihero.
And many people cannot deal with that. Many people (including most of the people who gave the book negative reviews on this site) seem to want the lead characters in the books that they read to be either obvious good guys or at worst flawed good guys. Well, if you think like that, then this book is not going to be for you. Walk away now and go and read Harry Potter again. And when you've finished that, move on to Dragonlance or something.
I mentioned what has been described as the author's "strangled prose". SF critic Dave Langford referred to Donaldson as suffering from 'OEDemia'. In short, Donaldson loves his thesaurus. He will use words that are to say the least, uncommon. This never really bothered me, but it might bother you. Again, be warned.
Donaldson's world isn't fleshed out anywhere near as well as other epic fantasy settings, he didn't make up his own languages and he lacks the gift for good fantasy names (yes, there really was a High Lord Kevin). But somehow out of all this, Donaldson came through with one of the great achievements of the fantasy genre. No fantasy author has taken so much trouble over one character as Donaldson did with Covenant. (Let's be honest, most fantasy authors, even the good ones, tend not to waste time on character development when they could be inventing three different languages and drawing maps of their world...)
Much of this first book concerns Covenant's struggles in coming to terms with whether 'The Land' is real or not and the fact that he is healthy, not leprous. In The Land, he is a hero; back home in America, he is an outcast leper. There is a quest involving characters going from point A on the map to point B, just like in many other fantasy epics. Here though, the journey is as much psychological as geographical.
So like I said, not for everyone. It's not a book to persevere with either. If you don't like it after the first few chapters, you won't like the rest of the book. Or the other two books in the trilogy. Or the three books in the 'Second Chronicles'. Or the two books (and counting) in the 'Final Chronicles'. But you might be in that minority of readers who believe fantasy can be challenging. And if you are, you might, just might, think that Lord Foul's Bane is the start to one of the best fantasy series ever written.