Here's some impressions and a list of mine that I'll keep going as I explore. I'll assume that people have already read about what was going on with DP4 and move on from there. I'm just going to list them in alphabetical order, not of importance. Remember to make good use of that feedback link in your dock and let Apple know about everything, so that we end up with the OS we all want. Well, of course, there's the nice bouncing start-up icons, the easier to see triangles for active apps, and the dividing bar for apps and documents and active windows, but you can also now add documents directly to the dock for future reference.
Installations are just another process that runs along side other processes.
Surfing the web while installing - what a concept. Still, they indexed the important stuff, which means faster finds in general. Wake-up time does indeed seem to sit at around 1 second. Well, you can connect to servers fine, but you can't connect to another Mac using Appletalk just yet. Can't even see the local network, it seems.