I would ask the same question of why people like it. From everything I've seen....
-Apartments seem annoying rather than interesting. An apartment is just a house with obnoxious neighbors that never go away, as well as an extra obstacle that keeps your sims from sleeping. I don't like when my Sims constantly have to spray the monster under the bed, so why would I like constantly banging on the neighbor's door? Why would I enjoy if my neighbors can just walk in on short notice and act like my home is their home? There's a reason it's called "my home" and a reason doors have locks, but apparently in San Myshuno, these concepts don't exist. Enjoy neighbors barging in to drink your water and leave dirty dishes.
-Festivals are recycled content, save for the Flea Market. A 20% success rate is terrible. I really don't see the purpose of going to a festival to do things my Sim can do at home, especially when one of them is notorious for making married sims cheat on their spouse. The rewards for visiting are ugly T-shirts you'd probably never wear again. Woohoo~
-Why are the food recipes a selling point? I don't care what my Sims eat, especially since I'm personally not a fan of the calories system. That system just means my sims have to work out regularly, which is obnoxious for some. I just cook Fish Tacos and other 0 calorie meals all day. But oh boy, now there's new recipes that...don't really do anything special, but apparently I'm supposed to be really excited about that new texture my sim interacts with.
-The new careers seem pretty bad. The BEST earning career is actually mediocre in the grand scope of things. ~9k a week is about the average pay amongst Sims careers, and the best paying one is just below that. I actually like low-paying careers for a bit more realism, but I think it's important to have variety and a nice mix of low income and high. The best earner seems to be internet celeb, though that requires excess work in your off-time, otherwise it's mediocre; similar in concept to the writer or painter careers where the cash is more to do with a skill than with the career earnings. More importantly, the career rewards are....non-existent. I saw the career rooms posted as images online....man those are sad. They're all base-game furniture with 1-2 new items, meanwhile the other careers can fill an entire room with unique furniture.
-UGLY clothing. Some of those I saw I had no idea what they were even supposed to be. The clothing is like the Sims team made it a goal to make "noisy" clothing as a theme. They definitely succeeded...
-Extremely boring city. Go compare Windenburg and San Myshuno. Windenburg for example has a huge neighborhood connecting some commercial lots to the start homes. If you walk around, you can see plazas with Sims playing chess amongst some greenery, some select locations to paint with an easel set up, a plaza with a fountain, some statues, etc etc. If you go to Diskothek Pan Europa I believe it was, then you can again see fountains and statues and lots of nice stuff you don't really see anywhere else.....now go back to San Myshuno. What do you get? Four lots encircled around a central plaza, with one commercial lot per neighborhood. Wowowowowowowowow how exciting! It's absolutely mind-numbing to me that they built an expansion pack that focuses on a location, and the location itself is the most dull they've ever produced because every single neighborhood has a recycled layout with nothing special.
-Again, why should I buy this? What exactly is the selling point? Where's the must-have feature? I know I buy Get to Work for the careers, I know I buy Get Together for the clubs....but why should I buy City Living? Certainly it's not that bland location. Certainly it's not the festivals that recycle base game content. Certainly it's not for the careers with far less detail and depth than Get to Work's careers. Certainly it's not just for the food or clothes....but what the heck is left!? Oh right, the Singing skill, and I refuse to believe one skill is worth $40.