Reading many reports that original iPhone 3G becomes quite sluggish after installing iOS 4. Not impacting all other iOS 4 compatible devices. Maybe best to stick with iOS 3.1.3 on iPhone 3G.
Did upgrade my 3G too.
Was slower. But after performing 2 Hard Resets some apps seemed to speed up.
but I have to say that my 3G is nearly full (4GB free).
But I've lost WiFi!!!! No way to connect except to my own router if the iPhone is directly near it!
All other known Wifi networks are unreachable!!!
So don't upgrade.
The funny thing is my wife's and her sister's 3G iPhone just work after the upgrade!
I did delete my iphone now 3 times and completely reinstalled everything but the Wifi problems persists.
I'm waiting for the 4G to come to Luxembourg :-)
I have a 3G upgraded to os 4 and I have had no problems. I did use iNavx a little a couple of days ago and everything works fine.
I am really happy with the upgrade and all the new features.
The only real issue that I have, and that was the same with os 3, and that is that there is no SOG and my normal speeds of 3-4 knots.
Bazzer
With iNavX 3.1.1 I am adding some slow speed filtering to help the iPhone 3G GPS SOG. It's a non issue on iPhone 4 or iPad 3G.