Great... Well, assuming you like great food, people and diving, you can't help but have a great time. We just booked our 5th consecutive trip if that says anything.
You are presumably aware that they don't have AC, so it might be a little warm there, although there are fans and I understand some sort of special ones of same sort are going in at some point. Some good bug stuff would likely be a good idea if you plan on hoofing around in the jungle at all (and you should do that, there's lots of trails... )
I would also recommend borrowing a kayak and doing a little island exploring. Just be aware of the wind and take water to drink. We paddled right over some large crocs one day!
The diving itself is as easy as it gets. Odds are, Arthur will be your DM, and Ed will be your boat guy. Both are excellent and fun to spend the day with. Diving is generally "out and back" after each dive since most sites are very close. The best diving (IMHO) is over at Halfmoon Caye, although it's very nice around Long Caye and Hat Caye as well. Most of the diving is light drift diving, although not all. I maintain it's the best overall diving in the Caribbean, and this was supported by an old friend who recently visited. She has dived all over the world and agreed that it was the best diving in Caribbean as well.
Beyond diving, eating, exploring and sleeping, there isn't much to do... take a book or two... perhaps something you can leave behind for their library.
If you want too see some pics, click on my website link, or FB link. Most of the warm water pics are from Huracan. FB has some specific Huracan galleries.
And if there's anything else I can help with (like carrying your bags and gear on the island???) feel free to ask!