I don't know how to express this, but melancholy is the word when I was in Chou Chou sim. The place is so pretty that it can bring tears to your eyes. Serene yet gloomy, it just somehow gives you a heartache in a good way.
It's a great sim to take pictures without any need to photoshop them. Dress up in your fanciest gown that you have and enjoy Chou Chou.