We had a great cruise with Handspan. Do your research before booking a Halong Bay cruise. To some extent, you absolutely get what you pay for. The day we embarked, several people died in the bay when the tender boat taking them to their boat was rammed & sunk by another junk. Our guides were much more strict about life jackets on the way back.
On board, the food was great, the accommodations comfortable, & our guide was attentive & knowledgeable. The scenery is stunning. Do it sooner than later; the bay is starting to fill up with garbage.