Since I am transitioning to sociology from another field I cannot speak particularly to sociology grad school. However, my experience in another master's degree revealed that it is not that much more work than undergrad, but that the work you are doing is different and requires more self-determination to not procrastinate. Instead of doing lots of little things all throughout the term, there are more papers/projects that are all due around the end of the term. Also, when there are tests, they are more likely to be essay based and less likely to be multiple choice/matching. It seems that there is less regurgitation of what you've memorized and more thought work and creation of written materials.
It might seem more intimidating at first, and in some ways it is more intimidating, but if you continue to work on things all throughout the term and do not get behind, it is not that much more time consuming than undergrad and should feel like more meaningful work. Just be very careful about long periods of self-directed time and your own tendencies to self-sabotage through various time-wasting mechanisms. Make a master schedule for your term with special focus on when papers/projects are due and include when you plan on getting smaller parts of these bigger things done. And if you have days that are unscheduled, create a schedule for yourself and you'll do fine.