Pros
Choosing your own workload is perfect for a busy person - if I know that I'll have time, I'll pick up assignments, and if I know I don't have extra time, I didn't. Also, their constructive feedback was generally friendly.
Kontras
I really struggled with meeting their expectations, even after two years of grading. I am not a dumb individual; I am generally fast in my work and I have never had issues meeting job expectations in any other jobs. I am a teacher so I understand how to give proper feedback. But it felt like if I managed to meet the time estimates, I always got my work sent back for revision. If I spent 20+ minutes on an essay, with my feedback being twice as long as the essay itself, then it seemed to pass muster, but then it meant I was only getting paid minimum wage. It often felt like they were just picking at my feedback simply to fill a quota. They did some restructuring over the summer, with some changes to their website and to grading expectations, so I had hoped things would change for the better. They are still figuring it out, so this may be a good gig in a year from now when the dust has settled.