Passage only barely looks like a science fiction novel, but it's probably closer to what might be considered the core of the genre than a lot of science fiction out there. It's fiction about how science is done and it's full of speculation. However, speculative fiction describes it very well.
Passage also pays tribute to classic literature. At times it reminded me of a Thomas Hardy novel.
You probably have to read Passage twice to really appreciate it, and I was frequently annoyed with it during this first reading. It seemed like 90% of the novel was filler about the main characters' trying to get from one place in a hospital to another while avoiding various people they didn't want to see, and failing or only just managing to make contact with each other at critical points. I didn't believe it - come on, these people who deal with life and death every day can't really be completely unable to say "No, I can't talk to you right now" to the people they don't want to talk to. And why are they relying on outmoded pagers and broken-down answering machines? They should send e-mail!
But the novel is built out of metaphors within metaphors, all about life and death and the stories we tell ourselves about death and dying, and in that context, the characters and their struggles make a great deal of sense.
The novel is also quite honest about - I was going to say death, but really it is honest about declining and dying. It doesn't offer simplistic answers, hold out false hope (mostly) and so on. I guess one thing that's mildly less than honest is that most of the declining/dying patients are wise and engaging. They have lessons to teach us about life and death and how to die. But that's true in real life too, except the messages aren't eloquent in the same ways.
It seemed to me that the treatment of the Alzheimer's character was especially sensitive. I don't have any direct experience of caring for someone with Alzheimer's, though, so I'm not sure.
The book passes the Bechdel test handily (there are a lot of women characters, and they talk about lots of things other than men). There is also a nurturing male character.
The main point-of-view character is killed 3/4 of the way through the book. I thought that involved a small bit of cheating on the author's part, since Willis sticks to her point of view almost exclusively and doesn't write in true omniscient narrator style. But she does briefly dip into other characters' points of view earlier in the book, so it's not a serious cheat. And the character's death comes as a huge surprise to the reader. It really is similar to how some people feel in real life when someone dies suddenly: But...but...that's not how things are supposed to happen!
The exploration of near-death experiences and scientific theories about it seemed quite plausible for the most part.
There's an amazingly eloquent and poetic description of brain death that's worth the price of admission by itself.
The chapter opening quotes are all "last words" from various famous people. There is a great variety, underscoring the triviality and profundity of dying.