Learning the cyrillic alphabet was very easy, it takes most students a week tops to learn it (so 5-10 hours). Learning the grammar takes a bit of time, but what's nice is that it very rarely deviates from general rules, unlike English. What's also nice about Russian grammar is that as long as you have the right case/tense, you can pretty much put it in whatever order you want. The part that kills me is the vocabulary. If you come from a western language, there is very little overlap in vocabulary.
For instance, English: Book ; German: Buch ; Spanish : Libro (but at least there, libro is kinda like library, so your mind can make the jump). Russian : K'nee-gah (Книга). To look at the total difference in vocabulary another way, imagine you were plunked down amongst some heart-surgeons (assuming you are neither a doctor nor fluent in Latin), and they just started talking about myocardiac fibrolations with endocronic infarctions blah blah etc, you might understand the "cardiac" but everything else you just don't have any context for. That's what a lot of Russian students run into even in their 4th year, each context area of life vocabulary has to almost be learned fresh from scratch. My professor told me that he learned it by *forcing* himself to learn 40 new words a day, and he'd go back and test himself on previous vocab-sets mercilessly.
All that said, you can get an eager student able to fend for himself in a Russian city easily in 4 semesters worth of classes.

