I have been using it in Vietnam for over a year without any major problems and I have suggested a few family members (who are not tech savvy at all) to use it too.

The app works very good on both Android and iOS (I personally use the iOS app because I flashed new ROM all the time and sometimes Titanium Backup of the app doesn't work). I tried the SMS a few times, the message normally arrives within one minute.

I am in Singapore and have been using it for a couple of months now. Works great.