This is a great course. I would highly recommend this course to anyone wanting an introduction to AI. The course itself was quite challenging and definitely worth the verified certificate. Although the quizzes were just a bit tough, the programming assignments were extremely hard (in a good way). The projects were fun and interesting. Do however note that they might suck up a lot of your time (20-25 hrs on average)
Also, this course has quite a bit of math in it. I took this course when I didn't know much of linear algebra and calculus and in some parts of the course, my mind was totally blank. Now , after finishing the course and after learning some of that math, I just went through those videos which had previously left me totally blank and I was able to easily comprehend the material. I also managed to pass quite easily even without the math ( I even left out a programming assignment and still got a 82%) so if you don't have the math knowledge, don't worry.
Coming to the involvement of the staff and TAs, it wasn't great. At the start of this course (around week 1-4), the staff was extremely responsive and helped out tons of students. However, as the course progressed, involvement went down. Technical problems would go uncorrected for days and questions would be left unanswered for weeks(Note that quiz errors were still getting corrected throughout the course if those errors were reported quickly). Even with those problems, the course and its contents, engaged me. Fortunately, the staff realized the problem and became active in the last few weeks, with even the course lecturer, who is truly an amazing professor :), helping us out.
All in all, a great course totally worth paying for the certificate. I unfortunately couldn't get the money ( :( 300$ is a lot in my country ) to pay for it but I truly enjoyed learning.