If you still have the 3GS, then the 4S is a MUST upgrade! I have the iPhone 4 and still want to upgrade. But I'll admit the move from 3GS to 4 was bigger than 4 to 4S. The fact that it's not called iPhone 5 means next near's is going to be even more significant. But the 4S (and iOS5 and Cloud) is quite impressive. I've had an iPhone since they came out, and have had every model except the 3G. Love it!
A friend of mine was trying to tell me to wait for the iPhone 5 but like you said, compared to the 3GS, the 4S is a pretty big upgrade. I'm really excited about the Siri technology. That looks sick!
