There is a BUG in it!
Everytime I klick on a Sim (in private houses) the sim's crystal is shorly gone and the sim stands straigt, even if he just laid or sat. If he stood before, he might teleport a little bit to aside. And the "thinking head" (whith which you can learn faster ((sorry - I'm german, and my game is too; so I don't know the english names)) ) is also gone, lays know on the ground and the sim's hairs are gone. xD
And sometimes also ALL sims around him stop their doing and stand straigt.

You often need to klick ON a sim, if you want him to phone someone, to give a party and so on. So it was not possible to me to keep this hack!