At SFO Airport last week and again earlier this week I made a series of international calls using my iPhone using Truphone. I also made some domestic ones as a test. The cost savings alone on the first call to the UK paid me back for my $7.95 a month Boingo Mobile account alone.
One think I also noticed was that at SFO the 3G signal level in some parts of the airport is not that strong. With Boingo my connectivity was faster and stronger to the 'net. As Om points out, many people are using WiFi on their iPhones to make up for the deficiencies of the AT&T network which needs more and more shoring up as more new users come on line.
First hand experience isn't wrong. Om and I both are pretty heavy users of devices, and putting the client relationships aside, I've been using both Boingo and Truphone almost since each company launched. They provide me the ability to be working anywhere and to save a ton of money. In addition to the iPhone I have the Boing mobile application on my Nokia N and E series phones as well as my Nokia N810. With Boingo on the N810 I can make real Skype calls over WiFi, as well as Gizmo calls. I can even connect to my OnSip.com hosted PBX using WiFi at the airport.
Bottom line. More and more there are neat ways to cut out the high cost of roaming, without skimping on quality.