Some people don't care too much about surprises. Me, generally I'm not that fussed about surprises in stories. Sometimes I'll try to keep life spoiler free, sometimes I deliberately seek them out - I'm not always patient. And I'd always prefer a party I knew about to a surprise party, because I'll already have filled out the time people want me to have a surprise party in with non-social activities.
I've also got to say that while I'm frequently picky about books, I don't find book reviews really help me as the main thing I'm picky on is the prose and nothing beats reading it. A look at first chapter and the blurb is pretty much all I need 9 times out of 10.
Also, interesting on cupiscent saying she doesn't summarise books when she reviews. I never did, before feeling like everyone else did so I should do. But I really think its better to talk about what sort of book it is, not what the story is... but excitement over the story seems to gain more attention.