iOS4 is dead slow on the elderly 3G, as you would expect
On the 3GS it's pretty damned close in performance to the iPhone 4 which is why you can only get the 8GB version new now (or I'd be getting a "cheap" 32GB 3GS). Interestingly, the 3GS has always had a nominal 800MHz processor running at 600MHz.
Watched a mate of mine demonstrate his iP4 (with the latest patch applied) drop it's signal down to nil whilst still on a call. No loss of audio either way, no dropped calls so far. Weird.
I'll be rolling back to OS3 on my old 3G (I sold my other iPhone) and if I run into any issues, I'll post them up. I might try a later iOS4 if it addresses the speed issue but I wouldn't bet on it. Frankly, I'm surprised it can run it at all in a non multitasking environment.
If it was known to be sluggish on the 3g then the update shouldn't be pushed down to 3g phones.
I'm downloading 4.01 as we speak - if that doesn't help then it's back to 3.whatever.
It's just time consuming - time I don't have at the moment.
How do we go about rolling back to 3.whatever on the 3g phones?
Once my 3g contract is up I shall be demanding a 3gs and according to the nice man at carphone warehouse thats not a problem. So if all goes well the only thing I've had to suffer is a slightly slower phone for a month and given the detrimental effect of OS 4 on older phones apple have (in theory) given customers an issue to demand an upgrade over. The last 3g phones are what? a year and a half old now so most contracts are up for renewal. in an ideal world I get to sell the old phone for £130 odd too.
The only apps no longer working are those that I.. well I stole them.
Release notes for 4.01 just mention the signal bars.