Everything interesting about the iPhone has probably already been written, but I got a new iPhone for Christmas and I am going to make a few comments anyway.
I am totally hooked on my iPhone and I wish I had gotten one sooner. I didn't because I couldn't convince myself that I wanted an iPod on my phone or a phone on my iPod.
I had it all wrong. The iPhone is the best mobile computing platform ever and it just happens to have a phone and an iPod. They are almost incidental.
I owned my iPhone for two days before I even plugged in the earphones. It is a great iPod, but doesn't hold a candle to my 120g classic for capacity and variety. I don't really like the idea of sucking my phone's battery with music, either.
But I am doing most of my personal email, most of my RSS reading, and most of my web searching/surfing and social networking on the iPhone.
The keyboard took a little getting used to, but I type almost as fast on the iPhone as I do on my blackberry now. I typed this entry with it. (iBlogger)
It is also a great gaming platform. Fieldrunners isn't just a "great game for the iPhone." It is a great game. Period.
It isn't a replacement for a sketchbook, but one can do simple doodles and contour drawings on it. (No. 2)
It is a brilliant calculator. Sci-15c and i41CX+ are both excellent apps. The fact that I feel the need for both probably says a lot about me - but I'd rather not examine that too closely. :-)
I have been spoiled for a while by having a blackberry with GPS and Google Maps and I am no longer willing to live without that functionality. The iPhone is better.
It is a great Twitter client - I am using Tweetie for almost everything Twitter.
It is a brilliant wifi locator (WiFinder).
Plus there are lots of totally new things you can do. Mobile Pandora is cool. As are SnapTell and midomi.
And in a pinch it is even a kitchen timer, diet aid, eBook reader, white noise generator, binaural beat machine, clock, flashlight, level, or a ruler.
I use my computers less now.