Quick review: Amazing and would recommend to everyone.  Everything is 5-stars.
Longer Review: This is my first time to Halong Bay so I cannot compare other boats.  This boat was simply fantastic.  
Service: The staff and crew could not have been friendlier and always working hard to make sure you are happy and get what you need.
Boat: There's a swimming pool, golf putting green, bar, dining area, and a large sun deck on the top floor.  Plenty of areas to relax and enjoy during your stay.  The boat is only 7 months old, so it's in excellent condition.
Food: The food was very good, but nothing extroardinary.  This is not to say the food was less than my expectations.  If you compare the food to a cruise line like Royal Princess and you rate them a 5 star, then Stellar would be 4 star.  To be fair, Stellar is a big boat and not a gigantic ship.
Price: from what I've researched, Stellar is more on the higher end.  I would say the value is there though.  The high price definitely meets what you are paying for.
Overall, everything exceeded my expectations and I have nothing to complain about.
Note: this has nothing to do with the boat, but don't expect to get wifi for 24 hours.  This is how halong bay is.