Les Mills' GRIT Series

So, I used to take a Cardio Strength class at my YMCA on Tuesday mornings. I got there this morning to find out the class had been replaced with two 30-minute Les Mills' GRIT Series classes . I am pregnant, but have been exercising the whole time. Apparently, however, the class is so hard that they won't even allow pregnant people in it. Has anyone tried it? Or heard of it? Our gym is one of only 25 in the country offering it right now. Just curious.