I've been using it for a fortnight now and I have a few additional thoughts. Overall I think I like it more than I did when I got it but there are a few annoyances.
As a basic phone it has proven to be better than I'd hoped - making\receiving calls is quick and reliable
Battery life is slightly better than I expected. Under my normal usage profile it's probably good for two to three days between charges but that drops rapidly down to less than a day when I make extensive use of data. I don't make many calls so for someone who spends a lot of time talking it is probably only good for a day or two at most between charges but on average it is better than any other "smart" phone I've ever used (and I've used a lot). What surprises me the most is that battery life is worse when using Edge\GPRS rather than WiFi for data.
The WiFi stack is excellent - the whole networking stack is better than any other device I've ever used.
The hardware mute key is something that every phone should have. This isn't new or unique to the iPhone, all the Palm Treo's have it as do some other phones, but it is universally missing from Windows Mobile devices and I'm not aware of any Nokia\Motorola\Samsung phones that have one.
The touch screen's ability to recognise finger tips and filter out all other interactions is amazing. It's a simple idea that you don't really notice at first (which makes it even more amazing) but it's done very well and it transforms the touch screen interface from a kludge to something that is a huge advantage.
Despite the brilliance of the touch screen for general UI purposes the on screen keyboard is a very poor substitute for a real QWERTY keypad. It's usable if you are stationary and focused entirely on the device but there's no way you can use it while walking or distracted in any other way. The BlackJack's keypad is a vastly better input method.
The lack of the A2DP Bluetooth profile (high quality stereo audio) is stupid. You can have the full iPod experience integrated with phone functionality out of the box via the wired headphones but you can't have that with Bluetooth.
The camera is just average but the whole integration of the camera with e-mail works perfectly so I've taken to e-mailing pictures to myself rather than go to the trouble of syncing via a PC and I am delighted that I can now just take snaps and send them to people the way I should always have been able to on camera phones in the past but never did because the user interfaces were always so poor or the transmission mechanism (MMS) was so lousy. Despite this the camera interface on the iPhone is too basic and desperately needs a dedicated hardware shutter button - for one thing it is virtually impossible to take a picture of yourself (or yourself with someone else) which is something that I tend to want to do occasionally.
The lack of extended applications, whether they are from Apple or third parties, is a major pain. I want a proper e-Book reader and some games for a start and while the "iPhone Web App" concept makes a stab at that it is, frankly, a lousy user experience.
It looks gorgeous and feels great to hold initially but it is too shiny and slippery overall. I just know I'm going to have it slip out of my hands at some point. At a minimum it needs some sort of rubber\textured grip around the edges. Fingerprint smudges on the screen don't appear to be a problem.
It doesn't make enough use of the internal accelerometer\tilt sensor as a UI feature. Where it does work (when switching from landscape to portrait mode in various applications) it works well but it should be used much more.
The SMS interface is great. The simple and consistent implementation of a conversational chat layout for historical messages is wonderful.
The contact manager needs to add the ability to implement and manage groups. You sort of get this capability after the fact if you mail or send and SMS to multiple contacts but it really should be implemented up front. The Contact Manager should also be on the front page of the UI.
The Recent Calls application should also be part of the front page of the UI.
Device Management from a basic user perspective is poor. For example you can clear cookies\history from Safari but you can't manage remembered passwords. Cleaning up old messages in SMS or e-mail is a painful one at a time process (although this is fixed in V2 I gather).