Use the Retina Display for a month, without looking at a 3G or 3GS, then go back and look at the 3G or 3GS.
Yes, the iPhone 4 display is awesome. That's a given.You only say that because you don't have an iPhone 4, which has a vastly superior screen to pretty much anything out there right now, and blows the 3GS out of the water.
It's actually four times the resolution.i can say there's a big difference beetween my 3gs and my ip4... 24hrs would be enough to see the difference... dont forget it's twice the resolution now that's a huge bumps trust me... but with all due respect the 3gs is still a super smartphone... with 4.0 its A1 like steve would say....
ps. the ip4 screen looks better than the ipad screen!!