I finished 3 years but they changed the grading as I was doing the courses - I skipped a year due to personal circumstances. Wouldn't say I was fluent but I can certainly read a spanish novel, listen to radio and TV although I'm still hesitant to speak but that's more my problem than the school's.
It's fairly easy to get to a basic level - pronunciation is much easier to learn than french, for example, but the grammar gets progressively more difficult and requires a certain amount of work.
I'd certantly agree with elefantfresh - if you do the work, you'll pick it up.
You get a much better insight into another country if you speak their language and Spanish is third most spoken language in world, I think - after english and chinese (in all it's guises)