Is it worth the extra money to pay for the 5 instead of the 4?
Is there a big difference between the iPhone 4 and the iPhone 5?
The iPhone 5 has a larger display
faster internet (4G LTE)
if its "worth it" depend what you want, and how long you plan on using it.
IPhone 5 is just much larger and lighter than iPhone 4, as well as a faster chip, the latest wireless technology, an 8MP iSight camera.