The new Create-a-Sim in general is really intuitive, allowing you to push and pull at different parts of a Sim’s body in order to get the exact size and shape you’re looking for. Picking a Sim’s walk style, which can vary from “tough” to “feminine,” does a lot to express personality (and it’ll change to a slouch if they’re tired or an “I have to pee” walk when their bladders are uncomfortably full).
When I created Jess, I was immediately impressed by the appearance-customization options.