To be honest, I'm sure this will label me as a crusty, old Luddite, but I hate friggin' mobile phones.
On the benefits side, the only time I've needed one -- where I would most certainly die because I couldn't wait some 30 minutes to use some other phone -- is when I'm in a store talking with my wife. Hardly a killer app worth the monthly fees they charge.
And on the bad side, everyone calls mine thinking that my owning one is an invitation to interrupt my life at any moment they please in order to reach me. And so when I keep mine off most of the time for that very reason -- and instead check the voice mail at home or work now and then -- everybody seems to freak out because they can't reach me right this second on my mobile phone ... and hardly anyone thinks to call my home or work phone instead.
...Since 99% of the time most of the calls are pretty inane and non-urgent anyway. Most people seem to use them as a time-killer diversion. Kind of like a more social version of the Game Boy. First step out of the office downtown, and everybody has to yak about the most inane stuff before they make it down into the subway. Just pointless.
I'm about this close from tossing mine in with the sharks... Stupid, annoying device for the same reasons I hate instant messenger versus e-mail.