My fiance and I traveled to Honduras from 25 Jun - 4 Jul. We hit the Mayan ruins at Copan for a couple of days and then headed to Guanaja to the Villa at Dunbar Rock. Dunbar Rock only has 4 rooms--which is great because that means there are no more than 8 divers! The first couple of days we were there, we were the only guests. It was great to go diving with just the two of us and the dive master. I felt sorry for the people diving with Posada del Sol--it was a cattle boat.
The divemaster was the only English-speaking employee, but we didn't have a problem communicating with the cook/maid. The rooms were great, the food was simple (but good and plentiful), and the location was romantic.
Diving: The visibility was great and the water was nice and warm. The dive sites are all marked--very little coral damage. Every dive ended with a safety stop in a 15-ft area with lots to look at. I never felt like I was wasting a moment of my dives. We didn't see anything big (sharks, etc), but the variety of fish and coral was great. I took a couple hundred photos on my digital camera. The package includes 3 dives per day plus one night dive. The divemaster told us not to ever plan a trip there in September because it rains all the time causing bad vis.
The pictures of the villa on various websites really don't do it justice. The villa is beautiful and the rooms were nice.
btw-Nautilus isn't used as a dive resort anymore. It's just the building where the staff lives.
Overall, I'd definitely recommend Guanaja and the Villa at Dunbar Rock. We're hoping to get 6 friends to go back there with us someday and take over the whole Villa!