Flew Vietnam a in 2006, was bumped to first class as there were only two pax, one in each class. Hard product was dated but in good condition, soft was good food, sprits etc, beer was Vietnam local. I don't remember the entertainment as I worked most of the way. Shared lounge in Syd.
In general I would fly J in preference to a Y+ product, unless you are chasing SC's and points.