I've had my iphone for awhile now and I can't imagine how I'd get around without it.
I'd already been using ipods for awhile and I needed a cellphone so getting one was a no-brainer for me.
its saved my butt from getting lost when I was out of town, I use it daily to find restaurants, barbers, post offices, department stores etc.
the map search and directions feature is probably what I use the most on it. its like having google and mapquest in your pocket.
I also use the internet all the time on it. you can't imagine how handy it is until you've had real web at the touch of your fingers. I do a lot of ebaying and its really handy for when I get to the post office and forgot to print out someones address or to check what they paid me for shipping.
all the new apps are awesome too. I downloaded "remote" which lets me use my iphone as a remote for my itunes on my imac so I can be sitting on the couch and browse my library and play music.
theres lots of nay-sayers who say "well my nokia can do that blah blah" but until you've owned one and used it for awhile you just won't "get it".
theres soo many little things about it that make it great like being able to pull pics of your friends off their myspace page and use them as avatars for their phone numbers and being able to just touch addresses in emails and have a satellite view of where its at or touch phone numbers in text message and emails and have the phone automatically dial it.
theres a reason more and more PC stuff is going touch... its just very intuitive.