The material was harder but I found it easier than undergrad, if that makes sense. In undergrad there are distractions and competition between students. In my masters program we all were taking the same classes, so we all knew when to study and when to have fun. There was also no competition as the classes weren't curved, we actually worked together sharing notes, study guides, etc. My program didn't have a thesis so I didn't have to worry about that, and it never came up in an interview so I don't know if it matters or not.
I also felt that making that commitment really changes your outlook and I was more determined and totally revamped my study skills. When you have nothing to do besides be a student there is no reason you shouldn't get a 4.0 unless you spent too much time on other activities. I did a one year, but my program also had an 18 month and two year, and you had the option to go into a longer program if the course load was too much.
I would recommend Barry University in Florida as the Biomedical Sciences Masters program had its own building and faculty so it felt like it was easier to know your classmates and professors. The professors also usually worked together to make sure tests weren't all on the same day. It worked for me, and almost all the people I went to school with have been accepted into dental/med school.