I don't know about Vietnam, but in the Middle East(at least in Lebanon, Syria and Egypt which is where I've been in the past few years) 3G is usually way more expensive than DSL due to low data caps. I pay 10$/mo[1] and have a 100MB/mo cap + 0.1$ for every MB over quota. DSL is ~30$/mo and a 12GB cap(this is Lebanon). So at least in this part of the 3rd world 3G is useless for anything other than checking your mail, chat and the occasional google search.
[1] That is, over and above the 20$/mo for the phone line itself. So if I were to get a line just for 3G usage(so as to put it in a tablet or chrombook, for example) it'd be more like 30$/mo.
[1] That is, over and above the 20$/mo for the phone line itself. So if I were to get a line just for 3G usage(so as to put it in a tablet or chrombook, for example) it'd be more like 30$/mo.