I took four years of Latin in high school, and by far the hardest part compared to other languages I studied was the sheer number of things to memorize. Five noun declensions by five cases (more than that, really, but only five to memorize) by two numbers made fifty noun endings. Verbs were even more complex: four verb conjugations, four principal parts to memorize for each verb, three moods (that I can remember), plus the active/passive distinction. That's a hell of a lot of charts to memorize. There are patterns in these charts, but lots of exceptions to the patterns. Plus all the various ways the various moods and cases can be used. Here's a nice list of the ways the ablative case can be used: http://en.wikipedia.org/wiki/Ablative_case#Latin

Compared to all this memorization, getting the feel of the language, even though it was very alien to my mind, seemed easy.