Its the most spoken language in the world
The population of China is 1.5 billion people. 1 out of 5 people in the world speaks Mandarin Chinese.

It Helps Your Career
Speaking Mandarin Chinese is a great way to give your career and edge. Companies who export to China, import from China or have Chinese clients either here or overseas would prefer a bilingual Chinese-English speaker over someone who spoke English alone.
Don’t think this will ever be you? With the Chinese in population in Auckland increasing, anyone from a hairdresser to a corporate banker could see increasing job opportunities available to them if they can communicate with clients in Chinese. The demand for people who can speak Mandarin is increasing every day.

It Provides Business Opportunities
China is such an important market and business partner for New Zealand. Learning Chinese gives you the opportunity to take advantage of our unique position in New Zealand as a Free-Trade-Agreement partner of China. When doing business with Chinese companies and clients, an ability to speak Mandarin will place you at a huge advantage over your non-Chinese speaking competitors. Even an ability to small talk in Mandarin can help break the ice and forge strong business relationships. You can take advantage of the strong Chinese market if you can understand and speak Mandarin.

It opens the door to a fascinating culture and is a unique language
Chinese culture is said to be “divinely inspired,” and is the only culture in the world to have a continuous recorded history 5,000 years long. When you travel to China, you are enter a whole new world that is both very old and very modern. Chinese has a very unique writing system. Characters represent meaning, not sounds.

Its Easy as Pie
Chinese is really not as hard as it seems. In comparison with western and other languages, Chinese has:
• No subject/verb agreement (I be, you be, he be, they be)
• No tenses (I be yesterday, I be now, I be tomorrow)
• No plurals (one apple, two apple)

More reasons to learn Chinese are available here