Learning to speak Argentine Spanish has been full of challenges. There are quite a number of differences between South American Spanish or Castellano and the Spanish I learned in school, which was more Mexican based Spanish. Argentine Spanish has been heavily influenced by Italy. Studying in Barcelona for five months and learning Catalan did not help either. I can say for myself that the biggest challenge about learning Argentine Spanish is that I can't understand their accent! Of course, this frustration was much greater in the beginning weeks and now that I have a better understand of the different sounds and consonants, I am not giving so many blank stares.
Vocabulary and slang, which is a whole language of it's own in my opinion, are also different for each region. Grammar, thank goodness, is more consistent among all the different Spanish dialects. I took a Spanish linguistics class in college that gave me a better understanding of how words are formed and the distinct features of each dilaect. However, I do wish I had payed more attention to the section when we covered Latin America!
One thing I am ashamed to say, but I think is quite normal, is that I have taken almost seven years of Spanish classes and I am more self-motivated and more excited than I ever was to study! And another thing... shame on the spanish teachers who never made their students talk in Spanish in class.