Personally, I wouldn't learn Arabic not because of the fact that it's a difficult language, but because it has many dialects and, as far as I know, nobody speaks the standard Arabic at all. You, Sa, for instance, probably speak Egyptian Arabic, some Mohamed from Syria speaks Syrian Arabic, another Mohamed from Algeria speaks Algerian Arabic and so on. Same with the language that I'm actually learning, ‒ Chinese, which also has a lot of dialects, but unlike in the Arabic world, everyone in China can and is expected to speak the main Chinese dialect, especially the young generation. I like your language though and am planning to get better acquainted with it someday.

Sorry for that , but I dissagree with you.
There is no relation between the difficulty of a language and the number of their speakers ( that if we consider that the arabic speakers - as a foreign language - is big )
As an example : chinese speakers - as a foreign language - are growing rapidly , is that means that the chinese is easy to learn , of course not .
Deciding whether to learn this language or another should be based on some criteria :
1- The power of its country.
2- The opportunity to complete the study of our specialization ( PHD , ... etc )
3- The culture of the country.

4- The opportunity to work there.
And finally. sorry for interruption :) 

To the last comment, differences between Arabic dialects not exceed about 85-90 % but the most beautiful thing about Egyptian Arabic is It’s understood in other arab countries, It’s the most popular one. If you speak standard Arabic, you’ll be understod. No problem.

And for Ray, Standard Arabic is being used in newspapers, TV, etc. It’s still being used but alittle by cultrulal people, undergraduates, writers and so many people.

that's nice ray :)
But i really wondering how you from UAE and you don't speak arabic fluently ??  

Thats encouraging, I would love to speak fluent arabic