@Bigessay: I must admit that even I had trouble seeing right away how some of those photos overlapped. Unfortunately Photosynth needs to take things in smaller steps than a human brain. Some of those shots, though they contained the same objects, viewed them from radically different angles. Pages 6 and 7 of the Photosynth Photography Guide ( http://photosynth.net/howtosynth.aspx ) cover what angles should result in good synthesis.
@David: I think assuming that all Photosynth users form the same demographic is not necessarily right. Or, put another way, I think that when people experience their photos successfully arranged spatially as Photosynth does, the frustration that they didn't all match is, in many cases, equal to the satisfaction or joy that is experienced when they have.
It does feel like a bit of a tease to have such an amazing way to view photos and then have the last few paraded in front of you without a way to place them correctly within their peers.