I'm currently running 10.4.5 w/o any issues seems that .6 has caused problems for some people so the question is what does .6 have over .5 that I should risk problems for?
People who are having problems are the most vocal out of the community since they want a fix. I haven't had any problems updating my iMac or the ones at work. (Quicksilver 2002, Mirrored Drive Door, iBook G4 , PowerBook G4, and a Power Mac G5)
For what it's worth, I'm fine on both my iBook and iMac with 10.4.6. And again, yes, there are lots of others. And I've also basically given up on repairing permissions as being particularly necessary.