Playing more of it, I do feel the packs are not as fleshed out in content, though I still love mermaids.
For me, I would loved seeing the following:
-Seeing Sims swim underwater (I forgot how awesome it was to see my mermaids swimming from all angles and from below!)
-Underwater lots (I'm starting to miss this!)
-Babies/toddlers/children having mermaid features (even if it's just scales)
-Houseboats (man, I really miss this one so bad!)
-Actual lifeguard career and other careers or jobs that are not rabbitholes
-Mermaid transformation (ala Sims 3)
-Mermaids' drowning power not nerfed and is actually dangerous
-Seeing an actual Kraken (ala Sims 3)
-Adults playing with toddlers in the water (ala Sims 3)
-Maybe a bit more activities or games like beach ball or something
I'm glad I got the pack at a reduced price elsewhere. It does feel more gamepack-y, especially if one is to play this world by itself and not travel to other worlds or have other packs to flesh it out. Still, I do not regret buying it (at that reduced price). ^_^
While I do love the pack and feel more engaged with the mermaids in this iteration, I do feel something is missing. I can't quite put my finger on all of the elements, but I remembered there was a bit more content in Sims 3 regarding this theme excluding the mermaids. (Maybe it's also having a bigger ocean and swimming underwater or just having a bigger world overall.)