Once I had the large screen of the EVO, when I went back to the iPhone 4 I knew I'd never be happy again with a smaller screen. it was like when I got the 30 inch display at work to use with my MacBook Pro. There is no way I'd be happy going back to a 20" display- things would never be the same.
The price for that larger screen is a big heft in the hand and pocket. I'll admit I still really like the very small, very thin size of the iPhone 4 which I hardly notice at all in my pocket and is joy to hold. But, the EVO is not uncomfortable in the hand or pocket and to the extent it is bulkier I am willing to pay that price because I just can't go back to that small screen and tiny fonts- the bar has been set at a new level. I'll admit I am generally an Apple fanboy myself on many products, but that's not enough here. Get your brother to try a mobile formatted blog on the iPhone and tell him to then imagine reading it for the next several years every day at the small size. Then, show him the same mobile site on the EVO and scale the font up on the big screen.
Then, go to a regular, non-mobile site and have him go left and right over and over again to read an article on the iphone. Then, have him read the same on the EVO large screen, with text reflowing at whatever size he wants to fit the page.
Then, ask him to flick down a web page on the iphone and then on the EVO.
Play a high def you tube video on the iphone where it is smashed into a smaller box on the small screen. Then have him see the same video on the EVO where this does not occur.
Then ask him to call someone by a video call on Facetime- if he is lucky enough to find someone on WIFI (and your brother must also be on WIFI) at that moment and with an iPhone 4 turned on. Do the same using Fring on the EVO and ask him to call someone who uses video skype.
Yes, I admit the iPhone is elegant and the user interface and screen are great. But, all is not as it appears when it comes to daily use.