Yup, I got Panther about a week after it came out (I think I even did an unfinished write-up of it in this forum... I'm so damned lazy). Come to think of it, am I the only GTPer with Panther?
Anyway, I love the sucker. Actually, one of the best improvements (IMO) is how they refined Aqua... significantly toned down those stupid pinstripes, and made the lighter alternating color a gray instead of pure white. It makes an amazing difference in being able to stare at the screen compared to Jaguar's pinstripes. Though, I'm ridiculously anal about GUI perfection, so I go so far as to install
Max's theme to fix some of the inherent inconsistencies in Aqua (those ugly progressbars and scrollbars that Apple hasn't updated since the 10.0 PB, the oversize Apple menu, the rotting widgets, the Jaguar-style push-buttons, etc. etc.)
Exposé is absolutely great, though I admit that I haven't really gotten into using it all the time yet... I still instinctively press Option when clicking on the dock to hide the windows. There was a poll at MacNN, and it seems like it's easier for people new to OS X to get used to using Exposé full-time, while the seasoned OS X users still use the Dock, Command+tilde, Command+tab, or arrange the windows so you can click on any one at any time. I must say though - Exposé becomes significantly more useful if you also assign it to a screen hot corner or to a mouse button, because the F buttons are rather inconvenient, since that means hitting the button and
then going to the mouse. With hot corners, you just flick it over and it works.
I really need to start using Fast User switching before my mom finds a way to fudge up my system, but I need to find a way to easily transfer all of the Keychain settings to a new account. I'll do it someday. Fast User switching is so cool though.
Um, let's see... Finder's way better (I'm surprised by how much I've, um, "embraced" the sidebar), I don't really use Labels too much yet but I have a little bit (I'm more in the habit of using a million and one folders to organize everything). Oh, and, it's faster. Panther's Mail is good enough to switch me from Entourage (combined with the fact that updating to Office .5 caused my Entourage database to blow up).
So... yeah.