I've had a chance to check one out in person and I have to say that there are a few things that intrigue me, but really I'm more excited about where this is heading than I am about where it is right now.
After seeing what the iPhone does and how it works I almost want to change the category of this thread from [Cell Phone] to [Laptop]. It's really more of a computer than a phone - which makes sense since Apple is a computer company and not (until just now) a phone company.
What I like about the phone is the convergence of products. You have a phone, internet, email, PDA, camera, and video iPod in one device.
But there are so many restrictions for how you can use things. I got excited when I heard that this phone would have WiFi capability - no more slow expensive internet via phone companies. And while the WiFi is good, there is no network drive! How did they overlook this?
You should be able to sit at your computer and put files wirelessly on the phone that still sits in your pocket via wifi. Use it as a memory stick, wirelessly transfer mp3s, wirelessly sync with your computer's calendar and email. Surely those are the sorts of places where this technology will really have an impact.
I've heard people criticize it for not having bluetooth keyboard capability - and that seems like a valid concern but I don't think you'd ever really need it if your phone automatically synced with your computer.
In terms of being a solid phone it has a little ways to go. No 1-touch dialing. No contour to fit to your face nicely. Weak battery life (for a phone, not for a computer). I've heard that signal strength isn't wonderful. But apparently the voicemail interface is second to none.
Overall I'm impressed - but I'm more interested in the potential of future phones than anything else.