I'll start by explaining where I come from here. I have a bias against Connie Willis. It comes from two main sources.
Her story "The Last of the Winnebagoes" deeply upset me, because the major development in the world it explored was entirely too possible. For any of you that haven't read it, I won't give away what I'm referring to, but it's not the demise of the motor home. It's written well enough that it really made me think about how it would be like for me to live in that world, and that was very painful for me, especially at the time. And there was no comfort in being able to say, "But that's so far fetched, nothing like that could ever happen" -- something that extreme is unlikely, but not beyond conceivable.
Her novel Doomsday Book, in addition to being a time travel story (I loathe time travel stories, but that's a rant for another day), wasn't even a good time travel story. Two separate plots, one happening in the present, one in the past, and neither one really engaged me and neither one really ended up saying too much. But what annoys me isn't that it was a mediocre book, but that it tied with A Fire Upon the Deep for the Hugo. Which means that if Connie Willis' personal popularity had gotten her one more vote, the best SF novel of the decade wouldn't have won the Hugo at all.
So, ironically, I don't like Connie Willis because of a story that she wrote too well and a bad novel that won an award anyway. And I realize that my dislike is less than rational, so I decided to give Passage a try.
The novel got off to a pretty good start. Plausible, if not completely believable science (at least to this moderately well informed layman), and a plot actually about scientists doing science. I was just getting into it, and the main character started getting a little funny in the head, and the writing started getting a little less coherent and more stream-of-consciousness. I'm sure it was a deliberate stylistic thing -- the main character is *supposed* to be going a little funny in the head and the reader is supposed to be helped to feel it by the writing -- but I hate that style of writing. And it took hundreds of pages and a really really long time for that to resolve into a "She (Willis) can't do that, can she?" plot twist, and things picked up again. I didn't give up during the long boring middle, and by the end I was getting into it again, although the very end was somewhat dissatisfying.
I felt very constrained writing that by my own no-spoilers rule, but I still want to stick to it. But anyway, I'll give the overall book a 6 out of 10. The first hundred pages and the last 150 or so were dragged down by the 400 or so in the middle.