Law school is less work than I ever had during undergrad. Of course, I don't write 2 page briefs for every note case like some people. But serious, you read like 20 pages a night per class (which is usually like 20-50 a night total) and that is all you're responsible for until finals week.
However, law school is way more stress than undergrad because of the bell curve, the competition, and the fact that the final is 100% of your grade. Also, if you take leadership positions and stress out about sending out 1000 resumes for that 1l firm job, you have a little bit more work on your hand. Otherwise, law school is not that much work.