Tones are almost the easiest part. The Chinese characters are much more difficult thing to tackle, which a lot of foreign learners skip, but in that way you'll never be able to read anything written in Chinese. The article you referenced mentioned you need to remember 2000-3000 kanji (Which is the Japanese pronunciation for Chinese character), well you need to remember a lot more for Chinese.
You need to deal with almost everything the article claims to make learning English hard, when you learn Chinese. And it's often a lot more harder.
When it comes to grammar, English has much more well defined grammar than Chinese does though it might seem too flexible compared to many other European languages.
In addition, if you actually live in China, you most likely needs to deal with local dialects, which could sound like a entirely different language. That's why there are Mandarin and Catonese. There are a lot more inside China.
You need to deal with almost everything the article claims to make learning English hard, when you learn Chinese. And it's often a lot more harder.
When it comes to grammar, English has much more well defined grammar than Chinese does though it might seem too flexible compared to many other European languages.
In addition, if you actually live in China, you most likely needs to deal with local dialects, which could sound like a entirely different language. That's why there are Mandarin and Catonese. There are a lot more inside China.