Chinese grammar is significantly easier than Japanese grammar. But the number of characters you need to learn is a couple times more than you do for Japanese, and Japanese pronunciation is way way easier than Chinese (not a tonal language like Chinese is). Plus you have to deal with Simplified vs. Traditional Chinese... I can't imagine Japanese being more difficult than Chinese... at least on the whole
But now we're getting off topic I think...
I do agree about the 50% drop out number, it was about the same at my university.