It installed on my laptop in about an hour and a half, including verifying the contents of the DVD. (It comes on a DVD now; if you need CDs, you can exchange it by mail.) I didn't have any problems with the software itself, although two programs I use, CodeTek Virtual Desktop and the OS X tunnel driver, wouldn't run. Someone will no doubt update the latter; there's no update for the former yet.
On the whole, it looks good. Spotlight and Dashboard both work as advertised. I was mildly surprised to discover that the Dashboard yellow pages applet already knew my ZIP code, so I didn't have to tell it to look in Fairmont. I was disappointed in one bit: while the main Calculator application now has an RPN mode (RPN r00lz, d00d!!), the Dashboard applet does not. The system feels a bit faster, though not dramatically so.
I won't be installing it on the iMac for a while yet: I need to build Hercules for the predominantly available version of the OS, and that ain't Tiger yet. Supposedly, you can build for downlevel systems, but I haven't figured out how to make that work for packages built outside the control of Package Builder.