Me too, it'll be interesting to see how this develops. It seems like Disney is staying away from a lot of the stuff at Coco Cay and keeping the project modest, if only slightly more to do than what's at Castaway Cay. It's hard to tell much from the art though and the ultimate plan could see changes.
Something that I noticed was that there doesn't appear to be a Serenity Bay equivalent, which would be a shame. I would be surprised if Disney did away with an adult exclusive area though.
I've been to Half Moon Cay, which was great, but not as great as Castaway Cay. It had one massive beach instead of sections, the food also wasn't quite as good, although perfectly edible. We'll be at Perfect Day Coco Cay (not doing the overpriced water park) this June, so we'll be able to compare the three main private islands. We'll be at Castaway Cay in a few weeks, so comparisons will be pretty fresh.
Something that these three all have in common though is that they're exclusive stops for their cruise lines. Lighthouse Point will not be and that's going to be an interesting piece to follow. I'm sure Disney has plans to address that though.