That's all you really need to know.
End of review.
If you really want to know more:
Your Sim does not age, you can't create your Sim a family, your Sim will not go to work or school, etc. You cannot speed up the game so instead you get to watch your Sim walking slowly across the house/yard/whatever.
You get so many energy points that regenerate every so many minutes. Then you do mindless repetitive tasks to make money to buy shit to decorate your house. However, basic Sim actions like eating and sleeping do not cost energy (sleeping doesn't get you more energy though either).
The only other Sims you can interact with are your Facebook friends' Sims, which is kind of weird when you start getting quests telling you to profess your attraction for a Sim. You're encouraged to visit your friends houses and get bonus energy for visiting them and helping them out with shit like repairing their microwave or cleaning their toilet.
I don't think you can WooHoo. Which, honestly, could be kind of awkward when you think about it.
Some reason I only get romantic options for my female Sim with male neighbor Sims, which maybe I'm just not trying hard enough with the girls but I could see people getting offended.
My Sim is also, as of about 5 minutes ago, apparently dating another person's Sim and I don't really remember agreeing to this? Or maybe I was just clicking through all my in-game messages so fast that I failed to read the "Our Sims should date" one. I'm not going to read all those things, they're wordy and there are a lot of them. Accept accept accept oh wait my Sim is in a relationship now? Shit.
I wonder, if there is WooHooing, if you have to send a request for that. "Ryan would like your Sim and his Sim to WooHoo. He also thinks that you and he should do the same."
My Sim showers with her bathing suit on. Uh. Okay.
Remember the loading issues with Farmville/Frontierville? Where you'd do some work and the game would suddenly say "Whoops! We ran into a problem and have to reload." and then you lost all that work and had to go do it again? Yeah, it's there in The Sims Social too.
Building your house, which I know is the favorite part of The Sims for some people, is a dumbed down version of the real game. You only get pre-made room dimension options and then you have to wait for friends to come help you build it.
Plus if you really want to get anywhere in the game (finish quests/build new rooms of your house/build furniture/level up yeah that's right, your Sim has fucking levels now) you'll either have to spend real money for SimCash or have fun spamming your friends and news feed for shit!
UPDATE: You can, indeed, Woo Hoo other Sims.
And then you can inform the rest of Facebook about the fact that your Sim just got laid and you didn't.
Also you can trim another Sim's bush.