Just to add some experience into here...
I went to southern rural France last week and spent most of the time using Bouygues Telecom on 3G and EDGE.
3G speeds were amazing and anything I threw at it, whether it be Internet browsing, Facebook, speed tests etc, it took them with ease. I did one speedyest which came out at 14Mpbs download and 3Mbps upload which I thought was brilliant.
I also had experience of Orange F and Free which were both satisfactory in all of the above but just not quite as fast as Bouygues.
I also had the same experience in California earlier in the year. No issues with AT&T. Speedy for whatever I needed to do. This is all without using the special VPN as I have an iPhone so it won't work!
The amount of money I saved must be amazing. I used around 1GB in the USA with a couple of texts too so it's a really good thing to have available as an inclusive feature!