Vantaggi
I taught several sections for AwesomeMath last summer, and I had a great experience. I was able to teach remotely, they were flexible in which courses/times you were available to work, and the students were consistently engaged (even over Zoom).
Svantaggi
TA's who were assigned to help with my courses were hit or miss. Some were great, but others didn't really engage with students or help beyond the bare minimum required of them. After each course, teachers and students were encouraged to give feedback on TAs, but given the rotating nature of the position, I'd say your chance of having A+ help with your courses is more luck than anything else. You are required to work summer holidays, and taking a teaching day off mid-session for any reason might be tricky. I'm not sure if there is a formal system for finding substitutes for lectures.