10.1.3 = good things.
Have installed 10.1.3 on 3 Macs with no adversities. No lockups, no apps failing to open, no issues at all.. one iMac DV 400, one iMac DVSE 500, and one g3 iBook DVSE 466..
I noticed that visuals in iTunes are a LOT faster in the smaller and medium sized full screen only... on the iMac 500 I'm getting ~60 frames on small and 36 frames on medium sized full screen (lq) settings.. that's quite a bit faster.. no difference on large full screen.. it's still at ~24 fps.
REALLY BIG NOTICABLE CHANGE: Finder seems more optimized.. Large directories nolonger beach-ball.. I can scroll through my Applications drawers which have over 100 items in the show icons mode sort by name and not only does it come up initially faster, it scrolls more smoothly.. I thought this kind of optimization was only intended for 10.2.. it seems some of it found its way into 10.1.3 ... thanks Apple!
Dock: Show/hide still seems as unreliable but it seems more responsive for some reason.. when the mouse moves across the dock from icon to icon, the name change is instantaneous.. it seems to have lost all latency. As the other user said, ctrl+clicking up menus on the dock (right click) is instantaneous now too.. they have obviously been doing work under the hood. Genie effect seems much faster/smoother as well.
Mail.app.. fine.. and I see the encrypted SSL available under account edit options..
That's about all for now. The most important thing is that I'm not experiencing problems on any of the three systems I use (all gee-threes).. My experiences is that mostly only the people who have difficulties bother to post about the upgrade in these message bases, so the impression for some is that the upgrade is more harmful than good when in fact most people experienced more good than harm... truth be told only the unoiled wheel normally squeaks!