While I'm on the subject of great usability, if you're an avid SMS fan, you'll fall in love with the iPhone. Unlike most phones, the SMS Inbox is not just filled with loads of received texts, while your Sent folder is stuffed with all the texts you have ever sent. In fact the iPhone has no SMS Inbox or Sent folder, instead your SMS messages are sorted by contact, and inside each folder is an ongoing record of every text you've sent to and received from that person - kind of like an instant messenger log.
Of course you can delete these SMS message logs, but it is incredibly useful to have a complete record of text conversations, especially when one of your friends is denying something that you know they agreed to via SMS - the iPhone log may not stand up in court, but it should be enough evidence to settle a pub dispute.
For those of you who are worried about the iPhone not syncing with Microsoft Outlook, relax, the two play very nicely indeed. Once you've connected your iPod to your computer and fired up iTunes, you can select what portions of Outlook you want it to synchronise. The iPhone will even download all the POP3 settings for your email accounts, saving you the hassle of having to enter everything manually on the phone.
Email in general is pretty well catered for. Tapping the email button brings up a list of Yahoo Mail, Gmail, .mac mail and AOL, with an "other" tab at the bottom. Clicking the other tab brings you to a more familiar screen where you can configure POP3, IMAP or even Exchange email accounts. As already mentioned, the virtual keyboard on the iPhone is superb, so even composing relatively long emails is no problem at all.
Then there's the iPod part of the iPhone, which basically gives you all the functionality of an iPod touch built into your phone. With 8GB of storage at your disposal, you'll be able to fit a fair amount of music and video onto the device, but you won't be syncing your whole collection. I don't find the limited storage too much of a problem though, since it makes me more choosey with my music selection, rather than just filling it with albums, some of which I may never even listen to.
If the Apple Click Wheel was revolutionary (no pun intended), then the touch sensitive navigation on the iPhone is just as revolutionary. Searching through artists or albums with the device held in portrait orientation presents you with a scrolling list, but turn the iPhone on its side and the view changes into Apple's Cover Flow mode. Here you can browse through all your music, sorted by the album covers. Although Cover Flow is undoubtedly a bit of a gimmick, it's still very cool to see and use. Also the ability to just flick through your music (or any other list on the iPhone for that matter) by just swiping your finger along the surface of the screen just never gets old. I know I wasn't overly keen on this type of navigation on the HTC Touch, but that's because it felt bolted on, whereas it feels completely seamless on the iPhone.