I would say that the Great House is one of the nicest hotels in the city. I would choose this one over any of the others. It was clean, though it is true that there are tiny little ants in the bathrooms...don't expect much better in Belize City though.
This hotel was nice depending on the room that you get. The rooms vary quite a bit and most are decorated nicely. Room 15 is very pretty, but the music from the Smokey Mermaid (restraunt downstairs) is sometimes loud and may keep you awake. Room 14 is the best, request this one if you can. I asume 13 is also very nice. The rooms out front are nice, but not as modern. Beware of room 12, unless you like carnival decorations...creepy.
The service was okay depending on who is helping you. The Smokey Mermaid is beautiful, and the food is usually very good though pricey.