I'm happy with the price I paid (not retail) for build and buy, but the world itself doesn't add usable gameplay for me. I lasted about an hour in gameplay before I was done and back to the same old ways of living, just in a new and pretty world. I don't play any of the occults so mermaids make no difference, not that I think they have enough features anyway. Might make one in CAS one day if I'm feeling bored, but I don't spend much time in CAS at all.
The biggest annoyance was that I created a new save with only Sulani townies and there was not enough separation from the other worlds. Especially if you want to try and play it somewhat realistically as a remote location with an insular community. So even for Sims, it's not realistic that a retired fisherman who lives off grid and has never left Sulani is going to invite me to Geek Con, or want to go to the rave at The Bluffs. But at least I didn't have Eliza or Katrina turn up at my door like I've seen in some LPs.