Even if you've studied Castellano and are pretty well advanced, there's a pretty good chance that you'll be thrown the first time you have to deal with "el voseo" (the use of "vos" to replace "tu"), the unique accent (castellano is pronounced caj-te-SHA/ZHA-no, where "LL" is pronounce "SH" or "ZH" and the "S" before consonants is pronounced like the "J" in Jose) or the use of Lunfardo slang. Aside from internet radio, this is the only resource that I have found that allows one to become familiar with the way Porteños speak. Thankfully, then, it's a great one! But even hours of listening to Sofia's refined articulation won't prepare you for the cab driver who babbles "caquérda?" (como? ah, aquí (acá) izquierda). Of course Sofia is also utterly charming and that doesn't hurt, either.