If you really like Cantonese songs and movies, or want to move to that area, or really really like Chinatowns. It's not really a literary language, as I understand it, with only paperback-type novels and text messages ever written in the language.

I used to think it was really ugly, but it sounds nicer and nicer to me the more Mandarin I know, for some reason. The Chinese themselves seem to think it has a real elegance about it, or something.

If you plan on living in an area where most people speak Cantonese then go for it. I'm trying to learn Mandarin and Cantonese at the same time and it's pretty rough but I like Cantonese better. It has a nicer ring to it I think.

Cantonese is more fun to speak.

I agree, Cantonese has the more pleasant tone to it. The movies and songs so much more pleasant to listen too. I lived and worked in Guangzhou for two years, learned so many words which I found no-one complained about with regards to the pronunciation. However once I moved outside the Guangzhou, Hong Kong and southern regions, to Suzhou Zhangjiagang, Taiyuan, Wuhan, I found it a totally waste of effort. Whistling, pointing or signing would have been easier to understand and many often got angry that I did not converse in Mandarin.

When a Cantonese Girl start talking.....I really feel excited...............That's why i learned Cantonese........To me Cantonese is the French of China..........Damn i miss the sophistication of the Cantonese girls.............

It's a widely spoken language. So I think it is useful.

I think it would work better with locals in Guangdong. (And you can know what they're saying and if they're talking about you.)

To please the locals, and make a good impression.

You don't have to learn all... but see the difference saying "ni hao" and "zhao*"

*I don't know if I write it exactly, but it sounds like this

If You learn more - it also helps with communication with "less educated" persons, who may don't understand "plain putonghua".

Learning foreign language is a serious work, it is not a light divertisment.

In writing, Cantonese is 95% identical to Mandarin, but it sounds (orally) -90 % different. For example, I am a student : writing - 我是学生。 Sounds: Mandarin - Wo shi xuesheng, Cantonese - Ngo hai hogsang. So, if you want to read and write - it is the same with Mandarin, but if you want to speak it - it is another language.

Pronunciation of Cantonese is extremely difficult: Mandarin has only 4 tones of sounds, Cantonese - 9 tones (shengdiao), a foreigner hardly could operate them.

The main problem - you practically dont need it. In Guangzhou and in Hong Kong only about 30% of population cannot communicate neither Mandarin nor English, only Cantonese. But they all are most low rank service personnel (waiters, car drivers and so on), any cultural communication they can support in Mandarin or English.   Do you will study a foreign language just in order to communicate with waiters or drivers?

If you want to impress some pretty Cantonese body, it will be enough to learn just a few phrases (like this: how much?)  

Learning foreign language is a serious work, it is not a light divertisment.

In writing, Cantonese is 95% identical to Mandarin, but it sounds (orally) -90 % different. For example, I am a student : writing - 我是学生。 Sounds: Mandarin - Wo shi xuesheng, Cantonese - Ngo hai hogsang. So, if you want to read and write - it is the same with Mandarin, but if you want to speak it - it is another language.

Pronunciation of Cantonese is extremely difficult: Mandarin has only 4 tones of sounds, Cantonese - 9 tones (shengdiao), a foreigner hardly could operate them.

The main problem - you practically dont need it. In Guangzhou and in Hong Kong only about 30% of population cannot communicate neither Mandarin nor English, only Cantonese. But they all are most low rank service personnel (waiters, car drivers and so on), any cultural communication they can support in Mandarin or English.   Do you will study a foreign language just in order to communicate with waiters or drivers?

If you want to impress some pretty Cantonese body, it will be enough to learn just a few phrases (like this: how much?)