I feel Sims 4 has a lot of potential, but currently, it does feel like style over substance. The things, in my opinion, it does better than other sims games are:
BB
Although it is missing some features from previous games (would love stair variations!), building is a lot easier in S4, and less stressful. Not sure about 2 and 1 but in sims 3, I had to go to edit town to save. The game had a bad habit of crashing halfway through building, so although there were cool things like curved stairs, more often than not, I would end up losing house progress because of this. The ability to search is also great in S4, as well as the ability to move/copy rooms.
CAS
While genetics such as hair colour and eye colour are a step back from 3, clothing categories, age (excl. toddlers and kids), and gender aren't restricted in S4, which gives way more options. I hated creating elders in S3 because they barely had any nice clothes, even with the added on expansions. If I wanted to do a traditional elderly witch, I could have all her clothing match the supernatural theme, except for outwear, where they put 1 supernatural skirt in the category, but no tops. So her outfit would look really weird, and not match the 1800's vibe I was going for.
Where S4 really falls down is gameplay. For a while, I played S3 with only Late Night, Supernatural and High End Loft Stuff installed, and I did not get bored. There felt like so much to do, and sim townies never failed to do the unexpected. In Sims 4 though, non-player sims, even with full autonomy, are boring to watch. For example, if you visit a library in S4, sims will read books and do normal library tasks (expected) with little interaction, whereas in S3, depending on what traits your sims has, some will like libraries more than others (couch potatoes hate it) and do different tasks such as fighting, flirting, working together etc.
Traits in general also don't work as desired, because default traits (such as sad when someone is dying) tend to override a sim's personality. (I've seen this example given before, but) when someone dies around an evil sim, they'll get sad, instead of happy, even though they're evil and are supposed to take enjoyment from other's suffering.
Multitasking, while nice on paper, seems broken, since whenever sims are multitasking, they take 3 times as long to do any task (eg. eating, drinking) that isn't talking. It also feels like there are fewer gameplay objects and skills (eg. in IL, fitness is the skill for swimming) and my sim can get through them pretty quickly.
To make S4 more substantial, it needs better sims, as they are arguably the most important part of the game (being the title's namesake and all). While building and cas are great, they don't add much to the life simulator part of the game, which is how I got into the sims in the first place. At the moment, while S4 looks great, it often leaves me bored, and longing for more gameplay and unexpected events.
