Voseo and Vosotros
I am still a beginner at Spanish, and I was curious if it would be beneficial to spend some extra time learning conjugations for vosotros and voseo. I know vosotros is still used in Spain, and Argentina uses Voseo, but how widespread is the use outside of these countries? Are these concepts that will take a lot of extra time to learn, or is it something I could generally understand or pick up in conversation if I were to encounter someone from one of these aforementioned countries?
6 Answers
It's not that difficult to learn. Vosotros is just one more set of verb endings and voseo only involves a few tenses. I would, at least, learn to recognize the conjugations of the more common verbs. Other than that, you can leave an in-depth study until you think that you may need it. You certainly want to be able to recognize the conjugations when you read them in print.
This is the best article on Vos, written by our good friend Benz from ARgentina
Have a look at this too,
Difference between Peninsular Spanish and Spanish from ARgentina
This may help 
To learn or not to learn
Vosotros decidís...
Here in the US, rarely if ever used, but I like Q's recommendation, to be able to recognize (recognise) them! Of course, I'm not talking about Spanish tourists to the US or old Spanish families that keep it current... those are given!
It's very common only in Spain and Argentina.
