My situation is that I'm a perfectly happy 3GS user who has been happily living without multi tasking for the last 7 or so months. The only issue I have is that it's an absolute data hog. I switched it on in Johannesburg airport last Friday and got the 5MB roamed data warning (via SMS) in no time flat. With this in mind, I'm wondering if IOS4 is actually worth the upgrade. Are there any downsides I need to be aware of?