Best answer by hamster
The great thing about coursera isthat nothing "bad happens" if you struggle, find things hard and/or fail. The fact that failing doesn't matter is very liberating -- it means you can experiment and learn things you would have been too scared to try at school when grades matter.
So, if you are asking how 'intense' the assignments are because you are the type of person get anxious/stressed by exams my advice would be to just relax; Remember that failure is part of learning and that coursera provides a "safe way" to fail.
Lastly, I'd say that quizzes and assignments tend to be fairly forgiving on coursera. For example most quizzes you get 3 tries to pass. What if you fail? Well, your "punishment" is to wait 8 hours before you get to try it again.
In short: If you want to learn something just give it a go! You have basically nothing to lose and a whole lot to gain.