[adbge]

iOS4 makes the 3G nigh unusable because the phone is constantly forced to flush memory to swap causing the UI to hang while the OS waits to write to disk. So, no, do not upgrade a 3G to iOS4 for improved anything. (Well, the icons are a little prettier.)

[megablast]

No, it does not. I have been running 4.0 for the 3 weeks, sure it is a bit slower, and there are things you can do to speed it up (you shouldn't have to, but you do). But it is not unstable at all. It never crashes.

Is it worth upgrading if you have a 3G? No. You get some updates apps, better email, and folders.

[StavrosK]

He said unusable, though, not unstable... Do you know if I can finally add different email addresses for outgoing mail? I have 10 email addresses that map to the same inbox, but I need to send mail from all of them. Right now iOS 3 doesn't let me do that at all...

Does anyone know if this is easy on the Android?

[ChRoss]

iOS4 is just horrible in my 3GS. I hit "App low memory" error during my first hour of use, and now I need to clean apps in App switch manager to free up some RAM when the phone feel sluggish. It gives me additional thing to do. I only like the folder feature.

[glhaynes]

iOS doesn't use a swapfile.