Get to Work: I like it. It's not especially buggy (anymore) for me, but I wish the other workers actually got to working every now and again as well. Aside from the scientist career, I feel there's no one besides my sim doing much, so that's a bit sad. However, I've used the doctor and scientist careers (don't like police so much) + quite a large number of the B&B items many many times, and overall, I like the pack quite a bit. It's not perfect and I wish retail had gotten a bit more love but it's okay :)
Get Together: this one I use the least. I am not super fond of clubs but I very sometimes still use them. I hate the constant text messages, mostly because I wish the same sim wouldn't text me every day. Although sometimes it fits the story. Still, I like all the new venues that come with it, and don't regret having it. Just don't love it as much as most other people.
City Living: as opposed to GT, this one I love. It's probably my favorite expansion, closely followed by pets. I play in the city a lot, love the apartments (and, ironically, their restrictions - reminds me of real apartments lol), like using the festivals for dates (although I wish married couples would flirt less with other sims during the romance festival) and for teens to try out bubble-blowing, like how the neighbors work and the many lot traits. As opposed to clubs, I love lot traits and am happy they keep expanding this system. The careers are also very nice and the atmosphere of the city is great.
Cats & Dogs: I really like this one too. It's weird cause I never really liked pets much in TS2 and TS3 (except cats in 3 sometimes), but I really like them in 4. Most of my households have pets and I just like the overall realism of having these little four-legged creatures around. The vet career is nice too and Brindleton Bay is now my favorite place to live when I'm not choosing to live in the apartments. It's just so beautiful. Especially the textures of the wood (idem for Jungle Adventure, which I think, uses some of these textures as well).