Well, I loaded Mac OS Tiger this weekend.
All seems to have gone smoothly, other than iPhoto refusing to run afterwards.
(I expected to find some incompatibilities, but not with Apple software!)
Found a message from someone who had a similar issue, and they resolved it by reloading iPhoto, which is what I did. (deleted the old app and its preferences before re-installing).
That worked, but then of course I needed to update from 5.0.0 on the DVD to 5.0.2 the current release. Software update thought I still had 5.0.2. loaded, so I had to download the updater from Apple’s website and run it manually.
Now iPhoto seems pretty happy.
Dashboard is very slick, Spotlight seems good too – not much experience with it yet.