Going to agree with everyone. Wait for the inevitable birthday sale in September. Honestly, most packs aren't worth the full price. Expansions cost as much as a standalone 3DS game with way more content.
For me though, it was worth buying at full price. I acknowledge all the problems the pack has, but the pack fits perfectly with the stories I want to tell right now, I can get a lot of mileage out of mermaids, I love Polynesian culture, and Sulani is a great place to base by sims' lives around. I might be disappointed in the pack, but it's one of those rare moments where a lot of my specific interests line up. I just had to buy the pack right away.