Is Chinese hard to learn?

I am not a Chinese but have a strong command of mandarin. I really don't think it is that hard to master chinese. My eldest sister is a lecturer in teaching mandarin in one of the university here. She has taught many students who are not Chinese to speak and write Mandarin quite well.

yes.i think it's very difficult.Last night i chat with my chinese teacher.He say chinese characters tones have four tones and some characters is polyphone.Oh,it's too difficult.

hello,i am a Chinese.And recently i found a funny thing. that's i found most of us like to see the cartoon when we in the childhood.And we listen and watch the funny character.And day after day,we are able to communicate with each other.We learn the local language in the funny atmosphere.And i know that,if i wanna to learn more standard English,i have to learn in fun.And do every of you has seen The Tompsons? So,if you want to learn the other language,go to see the cartoon and have fun in learning.You will find it's not difficult to learn the Chinese.