I saw this advertised on the VN website, and I requested an upgrade on a flight from HCMC to Hong Kong. It seemed good value for $69 (no lounge access, but I have Priority Pass, so that's not a problem).

I don't have any status with VN, but I noticed 3 or 4 passengers get op-ups at the gate and the staff were telling them that economy was full.

Happy with the upgrade, not so happy with the poor customer service at the gate. Arrived at the stated time, waited in line for 20 minutes for them to announce that the flight would be delayed.