I studied abroad for one semester this year. It went so fast that I would have loved to have spent a whole year but my course wouldn't let me. Your time really will fly by, and I think you probably would get more out of your experience if you did a full year.
However, I had an amazing experience for one semester and made a bunch of new friends abroad, and didn't have to take a year out of my uni course back home. If you're willing to put in the effort and throw yourself in headfirst, one semester can be worth it.