I’ve installed Snow Leopard, and my laptop has not exploded! Hurray! Here’s a general report for those who are interested.
Installing the OS took about an hour–comparable to installing Leopard, and contradictory to data I’d seen saying that the install could take as little as 13 minutes. I don’t know why it took that long for me, but eh, it’s all good, it worked fine aside from that. But those of you who are thinking of installing this update may want to be prepared for that. (As a side note, if any of y’all did have faster installs than that, I’d be interested for general reference.)
Once it got installed, my system did seem significantly faster. In no small part this is probably due to most of the system apps now running in 64-bit mode. Browsing in Firefox is significantly faster, as is Mail.app. Launching Parallels with my Windows XP VM didn’t seem necessarily faster nor less of a burden on my CPUs, but then I tweaked my VM settings to take advantage of both CPUs and to use 1G of RAM instead of 512K, and then that helped significantly. I still need to see what happens when I jump onto my work VPN, though.
Apple’s data on the upgrade says you should expect about 7G of hard drive space to be freed up. I actually had about 12G freed, which was interesting; I went from about 31G free on the hard drive to nearly 43G. Makes me wonder if I had a lot of system logs or something that had built up and which got purged with the update.
UI-wise, I did note that yes, the Stack windows you can get when you click on things on the Dock are different now. If a Stack window has more icons than can be displayed at once, you get a scroll bar so you can scroll through them. And there’s a new little slider in the Finder windows to let you tweak the size of icons, which is kind of neat. You can make those icons as big as you like. Anti-aliasing of fonts seems to have been tweaked as well; I noticed that in Adium, IMing 
solarbird
Time Machine has been streamlined a bit. Dara and I were a bit worried that there might be issues talking to the laptop we’re using as a Time Machine server, just because Freya is a G4 and can’t be updated to Snow Leopard. But I observed no issues, and Time Machine was quite happy to do a brand new full backup up to Freya, 8G worth of data. And it’s been behaving fine ever since.
There are a few new desktop backgrounds. A couple of them have pics of snow leopards, which is neat, and I may have to copy those into the folder I’m using for random rotation of backdrops. There are also several of famous paintings, which is cool too, and then a few other random nature-y sorts of backdrops.
That’s all I’ve noticed so far. All in all it seems to have been a painless upgrade and I’ve gotten noticeably improved system performance, so it’s an overall win!