Learning the Chinese Language
I am afraid there is no universal answer to your question. Generally speaking becoming fluent in Chinese depends on how much time and effort do you plan to put into it. Obviously the more the better. I would say it might be easier if your native tongue is related to Chinese (for example if you know Japanese, you have a smooth start with reading and writing). Personally I spent a huge amount of time on mastering Chinese pronounciation, since mistaking the tones may lead to various misunderstandings. 

Some say it may help if you have ever played an instrument or generally had some musical education background (cause then you had ear training and can at least hear the tones properly). Chinese syntax is believed to be not so hard to master, since it is pretty fixed (comparing to my native language Polish it really does seem fixed). There is no inflection, but you end up with hundreds of characters to memorize instead.

So is it hard? I would say yes. But it's also a lot of fun and satifaction if you manage to learn it well. I hope this answer gives you somewhat of an impression of what it might be like to learn Chinese.