The biggest thing that stands out for me is the screen. Occasionally my coworker will get some new app on his 3GS or show me a web site and I'll look it over only to notice the difference in res right away. I'll usually have to zoom in a bit to read it whereas on the Droid, the finest text is discernable. Another thing is the one button. After using Android, it does seem a little archaic. And not being able to easily see and switch to the last used program is a big handycap IMO.
And despite all that, he often has to pay for the same Apps I get for free. One good example is Wifi Analyzer. The free ones for the iPhone sucks and the better one (that's free on Android) he has to pay for. Another one is Skymap. The one on the iPhone does not use the compass whereas Google's offering does. Now his is much smoother, I'll give it that but functionally, it's inferior. Barcode scanner is another one, the free ones for iPhone are garbage, whereas Redlaser (their equivalent to Barcode Scanner) isn't free. Google Goggles, another cool app, not available yet for iPhone. And except for the Nasa app which is I think is really cool on his (can't find a good equivalent for Android yet), none of what he can get or has, I care for (except for some of his games).
When it comes to games, the iPhone still rules, but I know that's not going to be for long.
The main thing about Android that makes me not miss my 3g one bit, is the fact that the Apps I care for and use often, I can get, and mostly for free. Yeah there were tons to choose from on the 3g and I often filled it up with crap only to realize most were 'cool' for one or two days and then just sat there. By the time I got rid of it a year later, I had only the apps/games I used and they were few and far between.
Honestly the iPhone got boring for me rather quickly and when I look at one now, that feeling still resonates. Not so much that it's old but just: "meh, been there done that". I think quite a bit of that came from the fact that deep down inside, I never liked Apple's designs and their philosophy. I also hated itunes. And it did not easily allow me to customize it the way I wanted it. I hated the stock look after 1 month and really could not change it without hacking it. Jailbreaking at the time was really buggy so I never bothered.
What drew me to it was I needed an all-touch device (that supported Exchange) with basic PDA functionality and a good web browser. Nothing came close to the 3g at that time IMO. Now that things have changed drastically , in retrospect I do have some regret in not waiting a while.