I'm Nepali by blood (born and raised in the UK) and I can tell you he's right on everything he said (although I don't speak Tibetan, so I can't be sure on the translations). I remember as I was playing the game just stopping after every gun battle or on the top of buildings just to look around and being astounded at how accurately they managed to replicate Nepal (obviously heavily influenced by Kathmandu). It really was amazing the amount of depth and detail they went into. Obviously there are a few dicrepancies but it did a better job than say... Indiana Jones... or every Hollywood film that's had a setting in Nepal.
I was also a little annoyed that they went to Tibet before meeting any Nepali's as I understand Nepali but not Tibetan, d'oh.