After upgrading from an iPhone 3G:

• Wow, this thing is fast.  Navigation, apps, typing.
• Autofocus camera is very cool.
• Video recording is even cooler.  And the quality is very, very good.  Much better than I expected.
• Voice control surprised me by working exactly as expected on first go.  The second and third weren’t quite as expected, but I think that’s because of the strange name of the playlist I was trying to play - “The Iron Game”.  Playing different artists and playlists worked great.

Edit: Voice Control actually really sucks.  I can’t see myself using this.  It only does what I expect around 25% of the time.