I'm going to break this down into sections before I give an all around score;
World: 9
Sulani is a beautiful world. The Sims team has an amazing habit of giving us beautiful worlds, and Sulani is no different. I like the amount of lots we were given and the sizes because while the world itself isn't huge, it gives me enough room to build community lots if I choose while still having room for families. I had no issues with undersea diving and houseboats not being added. As much as I loved those two additions in TS3 Island Paradise, the lag that came with it was annoying. So unless the team finds a work around, I don't want them in my game. My one gripe is the cave. I'm not opposed to rabbit holes being used in game play (i.e. work, school, holiday celebrations etc.) but it was pretty disappointing learning that the cave didn't lead to a mermaid grotto. There's a map on the wall next to the map that you complete, but that's it. There's nothing beyond that. I read the reasoning behind secret lots no longer being made was due to players not using them, and while I do understand not wanting to spend time or money on something you weren't sure would succeed as evidenced with past iterations, I don't think that would have been the case here. It would have been perfect addition to this world and I believe it was a missed opportunity. It just feels like it was left out at the last minute. I really think this should be something added in an upcoming patch like Newcrest was, or is added on Realm of Magic is released.
CAS Items/Build&Buy Mode: 8
The CAS items that came with this pack are amazing! Everything was so well done, and I was particularly impressed with the hairs released. Those have been the best collection of CAS hair I have seen since TS4 dropped. However, the items for males, children, and toddlers was still lacking, with toddlers not getting much at all. Same with the Build/Buy items. What we were given was beautifully executed, but it did lack certain items like island counters, and I would have loved more wall decorations. Not only that, but the sunscreen you buy isn't usable. I don't know if that was an oversight or if it is just meant to be a decorative bottle, but I see no point in its addition if we can't put it in our Sims inventory for personal use when sunbathing.
Mermaids: 8
I. LOVE. MERMAIDS. Hands down my favorite occult in and out of the Sims. That said, they could've been fleshed out a little more. I would have loved it if they had a power tree like vampires, even if it wasn't as expansive. There should be a power tier when it comes to mermaids. I'd love to see something like that added in the future.
New Careers/Activities: 7
I am happy that we finally were given the ability to give our adult Sims part-time jobs, it adds some realism to the game. Lifeguards should've been an interactive job though, much like the ones in GTW. I do love the new activities. I've had my Sims sunbathing and swimming in the ocean for the last week. I liked that the Sims team introduced a new system where we can clean up the island and that affects how the island looks, something that should be added to all the worlds in my opinion, or in the next generation. I'd like the jet skis and boats more if they weren't meant as single Sim use. I would have loved to take my Sims on a romantic boat ride.
Sulani Culture: ... Where's the rest of it?
We have ancestor spirits, banana leaf pits to cook, festivals...at some point, but where is the rest of it? Where is the dance that is specific to Sulani? Where is the ability to learn how to make food dishes by eating them and having the required cooking skill? Where are the stories specific to Sulani? The greeting? The skill that you acquire once you take part in the culture? These are things we got in Jungle Adventures...a game pack. Rounding back to the festivals, there should be notifications and invites for when those take place like they are in City Living. I shouldn't have to look for balloons or walk into a certain area at a certain with the hope that something may happen. This part of the expansion was such a huge disappointment, and it should have been a big part of it. I'll give it a 5 because I don't hate what we do have, but we don't have much as far as culture is concerned in my opinion.
Final Score: 7
The pack is somewhere between a GP and an EP. While it introduces some cool activities, a beautiful new world and great CAS/Build&Buy items, it feels incomplete. It isn't a bad pack at all and $40 isn't too steep for a game, but when you consider the fact that this isn't the only pack many players own on top of the base game, that's a lot of money adding up. With that money, you expect a certain level of detail. I do think it's worth the buy, but not at the price point given. I'd wait until a sale pops up to get this.