You have to get an international plan with AT&T to travel. I think the iPhone is pretty but I don't see it as much competition feature-wise, with many of the smartphones already out there.Travelling? Will you be using prepaid SIM cards? If that's the case, you'll need a GSM phone...and have it unlocked. The iPhone can't currently do this, so if you go outside the US, you'll be paying roaming and international charges with the iPhone.
I agree with everyone as it relates to the the first generation I-phone.
The attached link compares the I-phone to the Helio Ocean. The Helio's capabilities are compatible to all the other phones out there including the Blackberry. The I-phone on the other hand has less capabilities.
http://www.engadget.com/2007/06/30/helio-pits-apples-iphone-against-ocean/