I was going to skip getting this pack. I didn't like what I'd seen of CAS, and the only thing I wanted from Build/Buy was the woohoo blanket. But although the trailers were not intriguing the reviews were.
The one thing this pack does is make Sim dating fun.
Gone for me are the days when I push 2 Sims into "try for baby" within 24 hours of meeting each other. Using Cupid's Corner is a must now, and the selfies are hilarious. The first time I tried a blind date, my trial Sim wound up with a werewolf. The NPCs actually respond now. Even though my Sim didn't have green hair and wasn't wearing black or white clothing (his turn-ons), her date still wanted to go to her place when she asked him how it was going, and later asked her to move in with him. I understand that the NPCs will propose autonomously, too.
I'm playing rotationally, so it will be a while before I find out how my married couples are doing. One good omen is that I've encountered some of them sitting together on a bench on a community lot, sky-gazing.