"You don't need intelligence to learn written Chinese, just a good memory."
Is memory part of intelligence? But yes, the main thing you need to learn Japanese or Chinese characters is a good memory with an eye to detail.
It isn't med school.
The two big issues with learning Chinese are the characters and the tones. These two characteristics together are too much for many people.
But, like I said, it isn't med school-it's a school for people who are diligent, who can put off gratification-the gratification that comes with a language you can throw together in a month and say a few travel phrases and be understood.
I often see people experimenting with learning languages and some of them have some pretty severe ideas-studying eight hours a day, sleeping less, etc. Maybe that works for some people, but that's not my way. In general I have learned more just by doing a set amount of work every day and not stressing at all about the language. I think this works unless you are under the gun.