Depends on what you want to learn. You can learn pretty quickly a prescribed set of Spanish knowledge, stuff that gets you by in a city's hotels, cabs, restaurants...tourist Spanish. Learning stuff so you can have good conversations is tough, Spanish is just so structured differently than English. I have been working on it informally for 6 years now and can write it in a way most people can understand my intentions, but I still make a ton of errors. My spoken Spanish is a bit weak, but the good thing is all Spanish speakers are just happy you tried. Try that with those French @#!$!#$ I remember in Montreal I tried to ask some simple questions in French, out of courtesy because I took it in school. After about a sentence I got "please just use English". So much for trying, they can't stand a mistake or two to their precious language!
BTW, if you start talking like Newbie in Mexico they will think you are either a priest or a snob!
People there hate it when you use the vosotros form...