I would not recommend this phone for North America, in fact I wouldn't even recommend it outside of China. Now I know a some more about it and have had hands-on of it.. Phone hardware is good, it's mainly the firmware, which is a heavily customised version of Android called "Funtouch OS". One thing it's very China specific. Running Google services on it is not without it's problems apparently. And there's no custom ROMs available for it, like Paranoid or CM.
Another thing, it's actually the same company that makes Oppo phones, BBK Group, both their Funtouch OS and Oppo's Color OS are extremely similar, and can be rather buggy. But at least with Oppo, you have a choice of good custom ROMs available, and they do have international sales and service, Vivo don't have anything outside of China.