OK, I have to say that I'm now a bit disappointed by some users in this thread - if you don't know about something, like that country called China, then don't judge it like you are well informed and/or you can foresee future. Really. I grew up there, I left for overseas severals years after university, it's been 12 years, and I've seen sooooo many naive and biased opinions about China since then, to the extent that I've mostly stopped trying to communicate with people on this topic.
All right. Enough rant. Now back to the topic of Chinese language. I'm certainly biased and I only speak Chinese & English, even though I've tried Spanish, French & Japanese for couple of weeks to months at different stage of my life - just bear in your mind I'm biased - I think Chinese is quite a accomplished language with no obvious flaws, due to the fact that it has evolved continuously for thousands of years, rather than being invented by a bunch of scholars and put to use in the last 200 years or so. Yes I'm talking about Japanese

And Korean. And Vietnamese.
Learning to read/write, remember the characters & words, is a hard job, but it's the same in learning any foreign language. English has letters, letters form words, words form sentences. Chinese has strokes, strokes form characters, characters form sentences. See? Easy peasy.
Oh, btw, Cantonese is the local dialect of Canton province. It's not a separate language. Anyone who tells you Mandarin & Cantonese are two different languages are....well, not well informed.
Now to the juicy part - pronunciation. I now speaks English with a fairly obvious Autralian accent, and can sometimes fool people with a fake British accent, but I know native speakers can still tell. Just like I can almost always tell if someone's speaking Mandarin natively. To learn a different tongue, you sometimes have to pretty much forget your mother tongue altogether and re-learn how the muscles should move. Chinese is very different to any European language in term of pronunciation, mostly because you'll need to use a different set of muscles to make sound. Lots of practice is needed to master it, but well, just like your mother tongue, when you practice enough, you will get there
All I can say now is that Mandarin pronunciation focuses on the very front of your mouth - lips and tip of tongue. Whilst European languages mostly use deeper parts of the throat. When you get to the point of understanding what I mean, congratulations, you will soon be speaking flawless Mandarin
Oh, and I didn't forget what this thread is about

Learn Chinese, of course. Apart from all the material benefits you may gain by learning the most populous language in the world, it also opens the door to thousands of years of literacy, history, art, music, cuisine, architecture, well, everything. Here you go, my very biased two AUD cents