I am a native Chinese speaker, and it was an excruciating journey for me to learn English. My personal belief is that the reason lies in the linguistics, namely the Chinese language may be somewhat isolated in the language family, and there are few modern languages closed to Chinese. So for a native Chinese speaker, I think it would be equally painful to learn any foreign languages. Japanese and Korean sound just as exotic to me as Swedish and Finnish. Those Kanji in Japanese are of limited help.
I also have great sympathy to my ethnic Chinese friends learning Chinese as a foreign language, because honestly I struggle with Chinese even as a native speaker. (more often than I should, sigh...)
In my opinion, linguistically speaking, Chinese language is like an isolated city where native speaker is struggling to learn the "outside" while the non-native speaker is struggling to learn the "inside". This is in contrary to the native speakers of Italian and Spanish, where reportedly they can understand each other about 80% without any learning.
This brings to my question. Let's take English as an example, because of its prevalent use around the world nowadays. Is it more difficult for a native Chinese speaker to learn English as a foreign language, or is it more difficult for a native English speaker to learn Chinese as a foreign language? I am not expecting a definite answer, since it is not possible to conduct a quantitative experiment in this regard (let a person to go from native-Chinese to foreign-English, and let the same person to go from native-English to foreign-Chinese, this is not possible in a foreseeable future). But I welcome any relevant discussions and thoughts.