After doing a lot of research on TripAdvisor, we decided to book a 3 day/2 night cruise with AClass Opera for Nov 10-12. We didn't want the cheapest cruise but couldn't afford the $200+ per night cruises either. I didn't find a whole lot of detailed info on this specific cruise line so I wanted to provide a review in case anyone else needed more info.
The Opera boat is relatively nice and comfortable. We booked an Oceanview room for only $10 more than the Deluxe room and am glad we did as we were located on the 2nd floor. The Deluxe rooms are located on the 1st floor, which is the same as the engine room. It was noisy and smelled of diesel fuel whenever I went down there. Our cabin was cozy and clean, located towards the front of the boat.
The food was good unless you don't happen to like seafood. The kitchen will likely accommodate you if you don't, or if you have other dietary restrictions (we sat at a table with a vegetarian and she usually got her own portions of veggie food). Each meal (except for breakfast) is several courses (usually 5 or 6) so you won't be going hungry!
Now the biggest reason why we did a 2 night cruise was so we could get a full day in Halong Bay. Unfortunately this was also the day where we had the worst experiences. On the 2nd day, you leave the Opera boat and are put on a smaller "day" boat to take you around the bay. The guide described it as being "not as nice but it will be comfortable". It was far from! There weren't enough chairs on the deck for all the guests to sit on, so 8 of us were stuck sitting on the floor. They compensated by giving us 4 lounge cushions to share and sit on, but it simply was not comfortable. The worst was when we discovered the toilets on the boat did not flush and there was no toilet paper. Gross! Considering you spend ALL day on this boat, AClass should do a better job in chartering an adequate one.
As for itinerary, it was quite busy and something was usually scheduled. We wished more free time was allowed but I guess that's one of the downsides of being on an organized tour. There's also not as much swimming time as you would expect from reading their brochure itinerary and there was absolutely no snorkeling. If you do the 1 night tour, you won't get any swimming time at all.
All in all, AClass Opera cruise wasn't the best value for the money in my opinion. Halong Bay is beautiful though and should not be missed.
Last tip - As with the other cruises, they charge for ALL drinks on the boat, even water. So do yourself a favour and pick up a few bottles of drinking water on the mainland to take with you.