I have really enjoyed every Connie Willis I've read in the past (okay, the two I've read), and so I was disappointed that Lincoln's Dreams was just not as good. It lacked the emotional punch of the stories in Fire Watch, and is far too similar to Passage, which is simply a better book.
But Passage really does seem to be a reworking of the same ideas - dreams/near-death experiences take people to historical places (The Civil War/the Titanic) where they struggle with the meaning of their experiences and the messages they bring back.
And Passage does it much better.
Also, while I got at the end, finally, the central metaphor of the book, and it's an interesting one, the main character still strikes me as irritatingly passive. It's one of those stories where the guy falls in love with the girl with no conversation, and indeed, there is no substantive conversation between them over the rest of the book - he avoids ever engaging her in actual discussion or even asks her what she thinks is going on.
I'm struggling to explain this without giving away that central metaphor, but it comes down to this: people aren't the same as domesticated animals. Avoiding every important conversation in obvious ways, never actually engaging with the love interest, this is all irritating rather than interesting.
And the bottom line is, Passage does the whole concept a lot better, and without the bits that drove me crazy about Lincoln's Dreams.