An excellent friend, who happens to be in Japan right now, was the first one to tell me that you can generally tell how good a book is going to be simply by reading the first sentence. I just picked up "Ender's Game" by Orson Scott Card, which starts:
"I've watched through his eyes, I've listened through his ears, and I tell you he's the one. Or at least as close as we're going to get."
Solid first by itself. Taken along with the tension created by the second (and I think it's fair to take the two together) I judge it a strong open.
(Incidentally, I haven't actually read the Wikipedia page on the book. Since I'm starting the book, that would seem to be self defeating. I'll the Wiki entry out after I'm finished with the original text.)