In my experience I would wait. It doesn't seem to be 100% stable -- a few quirks that are more significant than something that would make it into a shipping OS.
The primary reason I installed it early was the unified mailbox. Some of my apps launch and then crash. Sometimes (rarely) things cause the phone to freeze. The only apps that do multitasking are Apple's own stuff, which they pretty much all did before anyway.
Just chill for 1.5 weeks. It's not going to be fun and exciting until all the 4.0-approved apps come through the pipe anyway (and those cannot even be submitted until tomorrow, supposedly).