Just to throw in a "me too" post, I had the exact same experience as the original poster. I ran the jailbreak on my iPhone4, and all was well. The Cydia servers were of course overloaded, so I kept retrying a few installs of basic apps like SBSettings. What I really wanted to try was MyWi. MyWi requires Rock, so I kept retrying the MyWi install or independent RockApp install until it eventually downloaded. MyWi requires RockID to be working, and Rock requires each RockID be unique per device. So I signed up for a new RockID, which prompted a reboot. Not sure why. The iPhone froze at the apple logo and never came out of it, even after an hour of forced reboots. It also wouldn't stay in DFU mode. Eventually I got iTunes to detect the phone in DFU mode, and the restore went fine.
I'm really looking forward to a few basic jailbreak apps, but I think I'll wait a few more days for things to stabilize.