Apple have released an updated iPhoto library updater, version 1.1. Just managed to successfully transfer a library from an old PowerBook running OS X Tiger (10.4) to a new MacBook running 10.9. It upgraded the 5GB library in less than 5 minutes and all seems well.
The old MacBook was running iPhoto '5 and the new one iPhoto '11.
See this Apple link for the download http://support.apple.com/kb/DL1523.