My coworker and I sure did
Well, there must be something wrong with my eyesight. I see the difference when the pixels are magnified, but when I put my iP4 next to my 3G, in normal magnification, I don't see that big of a difference. The iP4 has more of a yellow tint all over v. my 3G. Not unpleasant; just different.
If you want to check your vision, I can go to the front page of macrumors with iPhone 4 and read all the text without zooming at all. The tabs, under the logo the tag "news and rumors you care about" even the URL on the ads by google at the top, try that on the previous display.
I can't bring my self to cover it up with a screen protector this time around. It just degrades the quality too much!