I've been playing around with it for the past week. Here are my first impressions.
I've installed it twice (first time an upgrade over leopard, with a lot of software installed, second time was a reformat/install as the mac needed cleaning up). Both times, it installed in about 30-40 minutes.
Not really a lot of new features to play with, but what there is is well implemented and a big improvement.
Quicktime 10 loads up a lot quicker, and it's interface is nice (although it's interface is strangely reminiscent of
Niceplayer but is basically the iphone quicktime interface. Sadly (because I have a lot of wmvs), flip4mac doesn't seem to work reliably. Perian works nicely for other formats though.
Finder has been rewritten and feels a lot faster than it did before. I haven't got around to installing any of the software I need on it (haven't had time), so can't vouch for for how the software works.
One thing that suprises me. Bootcamp for Windows has acquired quite a nifty new feature. It includes a driver that enables Windows to read the Mac formatted hard drive. I haven't done extensive testing of it, but it doesn't seem to respect the security of the drive. It seems to allow the windows user access to all the files on the Mac HDD. As I said, I haven't done extensive testing on this, but it's something I'm going to have to look at when I am getting the Macs at work ready form the 2010/2011 academic year (so I still have a year). For security reasons, we can't allow the students access to all the files on the hard drive (even read only).