I have some questions for people who have the game.
1. It looks like they rebuilt the game to really focus on sim's social interaction. Is that true? And if so is it hard to keep them happy if you're not into socializing?
Yes, definitely this is geared towards social interactions. They look a lot more realistic now that they can juggle two or three actions at once and also talk in large groups of people. It's easy enough to keep your sims happy since there's a new smartphone tool that allows them to socialize/have fun/etc without any fuss.
2. How is the Sims AI? Multitasking? If someone is in their way do they still stand around like idiots/cancel the action?
It's pretty good actually! Sims can handle up to three tasks as long as none of them conflict with one another and it looks fairly nature. Of course they're still sims and as such do some pretty stupid things but that's to be expected from a sims game.
3. How are the work/careers? I hear a lot of basic jobs got removed. Can you still micromanage how they work?
There's a lack of careers in my opinion--a total of like 10 at most--and it's essentially gone back to the way it worked in the Sims 2. Your sim walks out of their house and disappears and time is set to fast forward. Every so often you get a notification about something that's happening at work and you get to choose. Yes, you can still micromanage how they work.
4. I've heard about decorations and clothing influencing their moods.. Is this a big part of the game? It seems really obnoxious tbh. It's like having to do several romantic interactions before you unlock things like woohoo or proposing, except in this case you have to have them in a certain room or design your house around mood modifiers...
It's not a big part of the game. Most of the stuff is the premium items that you get from pre-ordering the game. It's a couple of facial accessories and some outfits. There's also items that you find by looking throughout the public area of a neighborhood which can give off an emotional aura. This can affect your sims positively or negatively and is easy to toggle on/off.
5. Is there any challenge to the game and if so what is it?
I think the only challenge I can think of is the whole group interaction is phenomenal but when you're trying to build up romantic relationships, it's SUCH a pain. You'll have two sims out in an open lot trying to flirt up and a stranger will just decide to join in on the conversation, turning your flirty convo into "an awkward encounter" causing your romantic relationship to go down and your sim to become embarrassed. Also, the game allegedly get glitchy/laggy after several hours of play (20+) on the same save file.
6. Do they have personality traits and if so how much do they actually effect the sims behavior?
They do! They're a bit more limited as you can only choose three + a bonus one from whatever aspiration you decide to choose. They do affect social interactions with sims. Example, if you have a sim that hates children and a child tried to talk to them, the sim with the hates children trait would become very uncomfortable/mad. It's a bit extreme for some of them, but others are very casual and work like the ones in the Sims 3.
7. Do you feel that there is a good diversity of furniture and decorations? Is there a significant downsize from previous games?
There is a downsize but you have to remember that the Sims 3 didn't come with all of the furniture that is available currently. This is still a base game and contains, in my opinion, a fair/average amount of furniture/decor. Most of the items also come in a variety of colors which helps create unique rooms/homes.