Blue Remembered Earth. I do try (and often fail) to like sci-fi, mostly due to sprawl. I'm pretty sure that there is a cabal of sci-fi authors and they have a competition to write as many words as possible. I mock your puny three 400k word volumes! This one does OK with a vivid near-future, but now I'm half-way through, it's just words. Lots of them. There's really no suspense or pace. I must have read about two hundred pages and all that's happened is someone found a glove and some pages ripped from a book (you know, if I was reading something like Slaughterhouse 5, I'd be finished now). OK, there's a nice core mystery there, something that ought to carry the plot forward, but there's really no momentum. Maybe it will pick up, but really, what I've read so far could have been squeezed into a single chapter and not lost anything.
(I do, for the record, think sci-fi books can be big, after all describing an entirely new universe or future can be worthy of lots of words, but those words do need to advance a story. Otherwise I'm reading a literal description of what might as well be a really big garden.)