The non-surprise is, obviously, 3G. Everbody wanted 3G, everybody knew they were putting in 3G, then they put in 3G. Yay!
I think the push-style syncing of mail, contacts and calendar, while not all that sexy, will make a huge difference to users. Though boo that you have to pay for it. And ditto the GPS, better audio, better price, etc. Basically they did a nice job of incrementally improving what really is still the greatest phone around. I’m retroactively more impressed by how few manufacturing problems iPhone 1.0 had. If that thing had shipped half-done the press would have murdered Apple, but the bug reports have been eerily scarce.
Incidentally, I am of the sub-species of human that still does not actually own an iPhone, but only because I’m waiting for my Verizon contract to expire and am too cheap to dump it and pay the fine. I should be free just in time for the 8G iPhone. Which should look something like this.