I'm not exactly the best spokesperson for the iPhone. I use it, but I'm nowhere near enamored with it like most fanboys and can tell you outright it is a "limited" OS since they've clamped down on the stupid things.

• Not jailbroken - although I did do that to my first iPhone.
• Just upgraded to OS 3.0 today, but not exactly 100% thrilled with it (same for the iPhone, just gotten used to working around it)
• Can't tether between the two - despite their being an older app that got pulled that would have done just that. But I've yet to attempt tethering.
• Exchange files... I've just pointed my N810 (192.168.15.10) to my iPhone (192.168.15.3:8080) with AirSharing open, and saved the files that were in the Public files directory - this is where the full browser on the N810 is the best - you have to allow access on the iPhone, or it'll time out. And you can upload/select files via the browser to the iPhone too.

File sharing easily done. I'm cheating though because Air Sharing and DataCase both came out for free initially and I got 'em. As of 3.0 upgrade, I've been having problems with ftp on DataCase. But it's easily done via the browser to and from the iPhone.