divemaster: I was a huge Stephen King fan until The Tommyknockers. Bored me to death. Tossed it aside about a third of the way into it, and I haven’t read a single new thing from King since. Yes, I hated it that much.
Missy2U: One of my biggest disappointments was Koontz’s Strangers. I had read most of his early stuff, and loved Watchers, so I was jazzed for Strangers. Maybe a quarter of the way into it, I thought, “Oh, I get it. He’s setting us up to think (X) is happening. But that’s just misdirection; he’s really got something cool up his sleeve.” I kept reading, and it kept looking like he was heading toward (X), and I kept getting excited, thinking, “(X) is so lame, he must really have a good surprise for us.” At the three-quarters mark, I was getting really worried: “He can’t REALLY be headed for (X), can he?” And when he finally shared the big “twist,” I almost threw the book in the trash right then and there. I read a couple of other Koontz books after that, but it was just never the same.
TVeblen: Everybody has their preferences; I loved Name of the Rose. I couldn’t get into The Island of the Day Before or whatever it is, though.
Others: I loved Greg Bear’s Queen of Angels, but I had real trouble getting into the followup, Slant, and as of yet haven’t finished it. Too bad, because I generally love Bear; his Darwin’s Radio is phenomenal.
I also loved Card’s Ender’s Game, and I thought Speaker for the Dead was pretty good, but Xenocide was a slog, and I’ve been avoiding Children of the Mind and Ender’s Shadow.
I had Gerrold’s “Chtorr” series (Matter for Men, Day for Damnation, etc.) recommended strongly to me, so I was pretty excited about reading them. I got through the first book and started the second before I admitted I was forcing myself through them, like doing homework. Put 'em down, and never looked back.
Small tangent, to reverse the question: I tried to read Dune a few times, and never got into it. The first 50 or 60 pages are so dense, so laden with backstory, that I found it tough going, and couldn’t get through it. Then I’d pick it up, try again, and give up again. This happened three times. The fourth time, I decided, goddammit, this is a classic, I’m gonna get through this. And lo and behold, after the first 50 or 60 pages, suddenly, it was like a magical breakthrough, and the story took over from all of the setup details. I blasted through the remainder of the book, and devoured the rest of the series. I ran out of steam at the beginning of Chapterhouse, though, but I’m still glad I decided to bull through the opening.