All in all it's not that bad.
I'd rather teach 3 90 minute class with 90 students than 4 70 minute class with 120 students any day. Or 5 55 minute class with 150 kids a day. The amount of grading and paper work is almost unbearable once you get over a 100 students.
The only bad thing is that after about an hour your students will start to lose interest if all you do is lecture so spice up your lesson plans.
another plus is that you only have to teach these kids for half a year. If they are a pain in the butt class you will be very happy to get rid of them after half a year. However, with anything but block you get the kids all year long. Some classes I don't know if I could survive if I had to teach them the whole year.
There is research that goes both ways in favor and against block scheduling. Personally I think it is better than the alternatives.