Is there a big difference from iPhone 4 to 5?

I'm getting an iPhone. I've been saving my upgrade for the new release of the iPhone 5. Now I've realized I can update to the iPhone 4 for free. The thing is how much storage do they give you on that iPhone and are the updates of the iPhone 5 from the iPhone 4 worth $199 that I'd pay. I'm not so big on Siri. But if it's worth the $199 I'd be more than willing to pay it. I just don't want to waste my money. Any opinions would be appreciated.

No big difference beside size and speed.
and you can put siri on any jailbroke iphone 3gs or 4

I have heard that there's not so much difference. In fact they are a little different but not varied!