Our family of 6 including 2 elderly people are just back from the cruise. we booked at an excellent rate from our hotel Symphony (thank creaking bones for the hotel reco) The cruise was a great experience. We were at full capacity for 18 people. Only one couple were doing a 2 night cruise, the rest of us were at a 1 night trip.
The kayaking experience was fantastic. Out guide Nam went way beyond the call of duty to make us feel comfortable. he even took my inlaws on a fish village trip separately since they could not go kayaking.
the food was Vietnamese and so-so. We opted for the veg options and there was plenty to go around. The last lunch was at a hotel opposite the habour and that meal was great.
The room was small (we are on a ship after all) but very clean and had everything we needed. 
The public areas were comfortable and our co passengers were a fun lot.
All in all an excellent trip. At no time was a tip asked though the tip box was prominently displayed.
One tip I would like to give is book via your hotel if you get a good rate since you pay later and have some leverage in this Halong bay market where switching of boats is a norm.