After anticipation of this trip long before our arrival we decided to book through local tourist company Asiana Travel Mate,Hanoi office ,a well reviewed company with local offices throughout Vietnam.First complaint-we where told it was a 3 hour drive according to the leaflet and sales agent,not true it was four hours and at times 20 km per hour.In their defense they said it was a very long day trip,but the guide told us it was 3.5 to 4 hours as soon as we got in the car,so he knew exactly what we where in for!! After a long trip punctuated by stopping at places specifically to sell you things( oh and go to the toilet) you are dropped of at huge art centers and told you will be picked up at the other end! What the hell,all this as part of a 4 hour drive and a stop at a pearl farm that was not asked for or on the itinerary and again led out through a huge sales area( note we live in one of the pearl capitals of the world,so don't need to waste time on this( this happened on the return also) the cruise was a great boat was very traditional feel and friendly staff.Now don't get me wrong the destination is amazing,very amazing and deserves its title.Unfortunately the food on board was terrible to say the least,four hours later as we entered the car to return to Hanoi I was violently sick with food poisoning having to stop the driver at least 10 times to have to vomit on the side of the road.This illness lasted about 36 hours longer. I'm not a fussy eater and always eat local cuisine throughout Asia so this is not a story of someone with low tolerance,the lunch was frozen local food that was deep fried,possibly re- deep fried and was still a little frozen in the middle.
My advice is possibly take your own food hamper or not eat the food if you don't trust it.I haven't commented much on the fact that we had a private boat for just the 2 of us and we where pestered to buy trinkets a little beyond what was polite.
All in all a destination worth the effort but consider how you get there and its probably not a day trip