What are the perks of an iPhone 4?

I currently have an iPhone 3GS and I'm looking into the iPhone 4, what are some useful perks on the iPhone 4 not used on the iPhone 3GS?

Here is a good article comparing the two:

http://www.engadget.com/...-the-tape/

Some of the perks of the iPhone 4 are:
A much better screen
Better build quality
Better camera
Forward camera
faster processor

More apps available on iphone 4 and it also has a better display. Its pretty much the same as iphone 4s