What's your experience been with this, either as an author or as a reader?
As a reader, do you prefer to see the opening segment of a book, or a segment somewhere from within?
Does it matter, so long as the extract intrigues you?
Do you hate previews of books? Love them?
I recall being extremely entertained by the Baen website postings from Lois McMaster Bujold's A Civil Campaign before the book was published. The teasers only fed my desire to have the rest of the book.