


Anyone who has been keeping up with the trailers will have seen a few videos about "Smarter Sims, Weirder Stories", and it's more than true. Your Sims are far more intelligent, however some things remain from older games. Your Sim's moods will affect how they interact with other Sims and objects, such as an angry Sim will work out faster, and gain the skill more quickly. A Sim that has the trait "dislikes children" will get angry when they talk to a child. But again, it's still The Sims. Place a chair in front of a door, and they can't escape.
The new build mode has been improved greatly, and the Buy/Build modes are now all-in-one, but it's not without error. (From what I've seen, now this might change in the future,) the build mode is pretty amazing, but still has the issues of needing the walls up in order to grab doors instead of objects. Now remember what I said about the Gallery?

It's going to be an incredible game, and I personally am very excited to play it.
Sources:
Screenshots were by me, in the CAS demo.
Sims 4 Fact Sheet
Sims 4 Wiki