My special problem is a family in which there are people with Mac( and
iPhoto), and Windows, and me (with Debian). I want something that
works reasonably well on all three. And for which moving picture files
among the three is trivial. For this, iPhoto is not an answer. Digikam
is a candidate, but it is not Mac compatible, SFAIK. But all these
practical restrictions are subject to future developments, so none of
these opinions are likely to stand the test of time.
Also one family member has only 56kB modem access to the internet, so
picture sharing on the internet is not an option (for me).