Took a new 3G phone running 2.0.1 and updated it without issue.  Went to dslreports iPhone test page and ran the test with the following settings:

WiFi: 2,616 kbps
EDGE: 167 kbps
3G: 900kbps (had to reboot the phone to get a signal.  First switching from Edge to 3G rendered NO SERVICE)

I have noticed the pause from doing something in your CONTACTS and hitting your HOME button no longer leaves a black page for a few seconds.  At 250+MB there hopefully will be some speed increases for the user experience.  The 3G service is so poor where I live that I actually just use the EDGE network.

Apple provides no intel regarding the changes other that saying "Bug Fixes".