I just been there in December, unaware of the law. I did fly with no issues (even with police seeing me). However, in many tourist attractions they will tell you not to fly.
At the airport i forgot to remove a powerbank from my checked-in luggage (both in an internal domestic flight from Hanoi to Da Nang, and in an international flight when flying back to my home country). Therefore, the police called me in to inspect the luggage before passing security and just kindly asked me to remove the powerbank and place it in my hand luggage. They did not say anything about the drone (which they have clearly seen) and its batteries.
BTW, most people call it "flycam" and not drones.