They charge over $20 to ship to Canada, which kills the cost-effectiveness for me; unless I was to buy large volumes of minis -- something like 10 expansion packs. Which I guess isn't many for collectors, but it is for me.
My one experience with GO wasn't good, but this was 1-2 years ago when they didn't accept international credit card numbers. I paid via mailed cheque -- needless to say, it was a long time before I got my order. The thing that got my goat is that they had run out of stock on one of my items, The Standing Stone module, but didn't note it on the website and didn't contact me about it. They shipped my order minus the module, no refund or explanation in sight. I finally got them to fess up after a couple of e-mails, and a few weeks later I received a cheque from them to cover the difference.
All's well that ends well. I'm sure that all of their current U.S. orders go much more smoothly than this, but that was my experience.