Yea, in general, Verizon is for people that don't leave the US/Canade/Mexico. There are spots around the world where your phone will work (South Korea for one, at least my D1 did, data was iffy). Western Europe is just no, some of Eastern Europe yes, but iffy.
GSM is definitely the worldwide standard. In the US, it's a little behind. CDMA (thanks to verizon) is a more robust network here, though not by a whole lot anymore.