I've heard it's more RPG like than the sims 3. I love the Sims 3, and basically use it like paper dolls whose lives I can mess with. Is RPG element needed, or can you focus on other aspects?
At the very least, it's quest-driven. You need to accept a quest from the main menu before you even enter into Live Mode. The other Sims games are way more freeform in comparison.
Then again, I'm a little sick of having to tell my sims to change their babies' diapers and make dinner. And sitting here, watching them clean. So I use the motherlode cheat to get money to hire servants. Gosh, how I wish that worked in real life. :p
Here, you only need to worry about food and sleep, and Sims seem to be able to do these automatically. I have a servant to cook for my monarch. I noticed there's breastfeeding in the game. Don't know if that was a feature in previous games, but I thought that would arouse some trad interest.