The sound of the iPhone is much clearer and generally better than my old RAZR.
What I really like is a built-in microphone in headphones that allows making and answering calls without holding phone next to your ear. Second is handling of the incoming call while listening to podcast or music: it fades aways and after finishing the call, it slowly fades back in. Very nicely done.
But the best phone feature is seamless integration with my address book, which thanks to synchronization that works very well always the same as address book on my Mac. It offers classic "wheel search", list of recent calls, list of favorites and dial keyboard. What is really awesome is the easy to add or update information: for example, you receive a call from a friend that just got a new phone. After hanging up, with single click on the recent entry you can assign the just received number to an existing contact. And it is always that single address card you use - with address (that you can show in Google map with another click) or email addresses that you can fire up with single click..
Btw, this integration makes GMail on iPhone better email client than on desktop within the browser, because here you use (and can enhance) your address book, not the separate Google Contact list - which is, despite the recent improvents still not on par with address book application.
Compare that to the "hashtable" I had on RAZR where people with 3 phone numbers had three address book entries (e.g. Igor mobil, Igor work, Igor home) with no way how to "merge" them ...
Battery life is considerably shorter than I was used from the Touch, which I had to recharge once every 4 days (depending on weather and consequently amount of walking done). This declined sharply to 1.5-2 days when I left the WiFi on.
The iPhone needs his energy fix pretty much every day, if you use it heavily, maybe even more than that.
The Settings in General section shows you both actual use time as well as standby time. I run with location services on, WiFi mostly off (except for iTunes at home) and cellular on 3G. I also check emails, maps etc quite frequently, take pictures like maniac (its new toy after all) and listen to the podcasts or music a lot. In average day, I get usually 4-7 hours of usage (meaning that phone is not in standby but doing something) - like playing a podcast and that usually drains the battery.
I may need to review that after I get few more full cycles out - full charge and full discharge and test the standby performance ... as soon I manage to keep my hands of it ...
So far I have seen anywhere between 5 and 9 hours of use - really depends how much you are walking with screen on and observe the blue glowing dot to move - this drains battery quite a bit. Also watching video (as expected) is heavy and WiFi as well.
The battery life improves when you switch off 3G and bear the sluggishness of EDGE connectivity. It is still usable but much less fun. Right now, sitting in train to Montreal, EDGE is all have here between Alexandria and Coteau, and I call that lucky because we have been going through several No Service dark holes ...