Q: Lessons learned?
A: I'll never travel without the iPhone. Neither will I travel without a guidebook, a laptop, and a willingness to talk to strangers. I could have left the hotel an hour earlier each day had I been planning my itinerary on my laptop instead of zooming in and out of Web pages and tediously typing on-screen. And the phone holds you hostage to the strength of its connection and to its battery.

Q: Overall experience?
A: Since you are frequently staring down at the device, you can't help but feel cut off from the people around you. And moving determinedly from point A to point B as directed by Maps kept me from fully taking in the character of the neighborhood I was trudging through. (On the other hand, knowing that I could get terribly lost and that the phone would get me back to a metro stop let me amble down streets I otherwise might not have dared to explore. En route to the Izmailovsky Bazaar, I found myself fearlessly wandering a mile in every direction from the metro stop, and I eventually stumbled upon a farmers' market packed with root vegetables and freshly butchered chickens. It was the last thing I would have expected to find on a snowy February afternoon.

The Case for the iPhone
It's too useful to leave at home, so here's how to save when taking it overseas

Admittedly the iPhone didn't perform as well in Moscow as it does in New York, but that's mostly the fault of the Russian capital's slow cellular network. Still, the iPhone is my ultimate travel accessory: It works in nearly every country on earth; is a camera, a calculator, and a phrase book all rolled into one; and has built-in Wi-Fi that allows unfettered Web surfing. I cant imagine a ten-hour plane ride without my iTunes movies, several gigs of music, and language-learning apps to keep me occupied. But using an iPhone overseas can cost you a bundle. Here's how to keep expenses down. First, watch your usage. AT&T charges for data based on how much you send and receive. (An average e-mail is only about five to ten kilobytes, but photos and documents can be several hundred kilobytes.) Monitor how much you're burning under Settings. Second, avoid loading full Web pages and use mobile sites and apps as much as possible. Most important, visit att.com to see whether your destination is one of 90 countries in the Data Connect Global plan, which lets you prepay for 20, 50, or 100 megabytes, starting at $25. The cost is prorated, so cancel it as soon as you're home. If you opt not to buy a plan, keep your data roaming off whenever you're not using it.