I went to Timor Leste in August 2012 - weather was very good - calm sea, clear skies.
The coastal sites are excellent for macro, if you get the chance dive the pier as the soft corals are stunning and its very atmospheric.
I saw a Dugong at Artauro Island - and 1 diver spotted a hammerhead so if your centre goes out there it is worth it. we kind of jumped in at random places and just dived - was very great.
Jako island is didn;t think was worth the long trip out there. bit disappointing in terms of fish life and also health of the corals - coastal sites i felt were much better by comparison.
I was on a liveaboard, but that no longer operates there, however i did stay the night at Dive Timor Lorasae - nice enough place, friendly staff and good food in the restaurant at reasonable prices.
its worth the trip over there for sure, enjoy!