It would seem like a wasted investment if you dropped $200 for the S2, than dropped another $450 for the iPhone, when you could have waited a little longer and got the iPhone for $200. It's your money, so I can't tell you that you are wasting it, cause different things make different people happy. I will tell you this. I have an Epic 4g, and an EVO 4g. My gf has the iPhone 4s. It is a nice little phone, but I would not pay $450 for it, especially being used to a bigger screen. I bought the Epic with contract for $200. It was not a very good phone, so I bought a used EVO for $175. The evo battery situation got tiring, and the Epic developers have come a long way since I switched to the EVO, so I am back on it and loving it.
I will have to see though. My contract comes up around this time next year when we might be seeing a new iPhone. For me, going to iOS is like going from windows to iOS. It is the small things you notice after you have been with it for a while. If the iPhone has a bigger screen, it is quite possible I will give it a shot.