Apple's somewhat ambiguous release notes for iPhoto 8.0.1 state that the update improves "overall stability and addresses minor issues in a number of areas, including internet connectivity, keyword import, and slideshow export."
Users, however, are reporting some other major enhancements.
Speed Several users reported significant delays under iPhoto 8.0, particularly when switching modes. The new release delivers a noticeable boost of speed in various areas.
Faces iPhoto 8.0.1 may resolve a number of issues related to Faces, particularly one in which Faces categories inexplicably merge; in other words, two persons' faces combine into one face category. Several users have reported better results under this version. If you are still having problems, however, consult our previously published fixes.