I took a year of it in college and it was really fun. The grammar is pretty different, but often simpler than English. Tones are something you have to remember, it's not too hard really, though there are a few phonemes that aren't in English that you'll have to get used to; I found diagrams of the inside of the mouth helpful with that.

I was illiterate in Chinese almost immediately after the class ended, but I'm sure there are helpful resources for learning and retaining characters.