Well, when I saw the new Power Mac, I certainly sat up, but I did not say "howdy." Rather, I said, "What the hell is that, and where did our lovely Power Mac go?" (Some of you may have seen my post where I called it ugly...) At this point, though, it's grown on me, like many things I don't like at first that I really should (such as Metallica's new single, St. Anger).
I don't really think Panther is a major update (back! All of you! I have my fire extinguisher!). Sure, it brings some new features like Exposé and user switching, but it's not as big as Jaguar was. The OS is already almost completely stable, and almost everything works well, so stability and compatibility aren't a big issue. Plus, Panther detracts on the UI front by replacing the gorgeous Aqua with the blah blah blah brushed metal.
The rest I really don't care about, at least not at this point.