I played one zoi through most of the idol career track. The career gameplay is very similar to Sims 4, in that you go to your work lot and try to perform all your work tasks before the end of the day. Similarly to Sims 4, I didn't feel like there was a meaningful sense of progression in my skills and career. I went from having 0 in the career relevant skills like singing and dancing to having them maxed out in, IIRC, a little over an in-game week, in which time I didn't perform in any idol shows because that didn't seem to be implemented: work was always training, never performing. (It's possible this has been updated since I played, which was in April, or that performing is hidden behind the very last level of the career track, which I don't think I reached.) Like Sims, you never struggle to advance a skill or have any kind of challenge to overcome, you can improve at anything indefinitely by practicing alone. I started a romance with a coworker, but it wasn't very interesting: it didn't cause drama at work, it didn't affect how my other coworkers thought of me (which was mostly "not at all"), and it wasn't clear to me if the other zoi had any skills, interests or hobbies outside of work. Similarly to the Sims, I think we were at the point where I could have proposed after only one date, which mostly consisted of hanging out at the park. It seems like, similarly to Sims, the actual game mechanics are fairly basic and you need to invent a good deal of your own fun.
I liked being able to customize items by importing textures. The AI texture generator isn't any good, but the option to noodle around in GIMP and then put my texture on something in the game is neat. I also imported images to make custom posters for my zoi's room. There is also an option to turn a photo of an object into a 3D model of a decoration to place in your house or wear as an accessory, which I had mixed results with but was at least novel.
It's on the list of commercial failures in video games.