The thing is, BBC or other foreign media always push things like this in a way that Vietnam Government is against "human rights", and "freedom"... From my point of view, they just want to attack Vietnam Government and make it look bad, by telling half-truth. This is not the first time.
My English is not good enough to give you a clear understanding about that law, but it's not about "prevent people to discuss what is being done by the government".
The exact word could be more close to "bring down the government", and that I think no government in the world let someone do that "in freedom". I dont say Vietnam Gov is good, but at least they are not that bad to bring down right now. All the people that "oppose" Vietnam Gov always close to "bring down", and tell half-truth or lying, and related to foreign countries.
So I am fine with that part of the law.
The other parts are about management, providing and using Internet services and information.