May be too late, but I know there is at least one dive outfit in Djibouti. One is Dolphin Excursions, but they probably won't be going out until September. July and August are very hot (115F), so they don't dive much during those months. They can be contacted through Facebook
As far as whether or not it's worth it, I think it is, as far as diving is concerned. I certified there last year. The water is warm enough that no wetsuit is necessary, even at 80'. Lots of coral reefs also. Visibility is also really good. Just search Youtube for Djibouti diving.
As far as Djibouti itself... I would hardly consider it a resort location. The whole city is a bit run down, and on the outskirts there are large tin hut villages where all the destitute live. I was there because I was deployed at Camp Lemonnier for a little while. But I definitely wouldn't vacation there. The diving is great, though.