mandarin

Above all I am a Chinese myself. So I have to be as impartial as I can. But I really don't think it's very difficult, if you take character-learning as a fun. Because that is almost everything in this language. Because the pronunciation is easy to learn, with very regular rules and the grammar is easy, too. There are no flections. Of course there is some minor grammar problems to remember. But is there any language without it? The tones is a problem. That needs practice. And since Chinese characters is more than Chinese "pronunciations", so you should pay attention to the words. There are many words of similar sound, or even the same sound. That is what I think of. Hope it helps.