Spanish fansite ExtraSims wrote about The Sims 3 Generations from their time spent at the Madrid event.  Read all about it here.

Now, when a Sim is going to happen to the adult stage, the day of your birthday you can start to suffer a midlife crisis with special wishes that will have to get the extra points to spend on rewards for a lifetime. Unlike normal desires, if a Sim has a desire midlife crisis without meeting will receive a negative mood until it complies. Also, if you decide to promise you the desire will last until the crisis ends meet or in the Sim. You can distinguish this kind of desires from the rest because they have a special red background. Overcoming these crises, and receive points for happiness in life, you will get also a positive mood for every wish fulfilled. It is necessary to fulfill the desires during the crisis and that if you want you can send your Sim to the hospital for therapy and thus to achieve out of it soon.