Pros
This is a legit work-from-home job. You are scheduled according to your availability, which you submit on a monthly basis. I have never been penalized for canceling or changing a shift. It seems like an ideal job for part-time teachers and stay-at-home parents with a background in education.
Cons
There is almost no opportunity for advancement. Every couple of years, a program may accept applications for scoring leaders, but chances of getting those positions are low. As a rater, your day depends entirely on the quality of your scoring leader. Most SLs are fine and will treat you like a human being, and some might even make you feel like a colleague. Others have poor social skills, are needlessly condescending, and a couple have been outright hostile. There are limited channels to provide feedback on a scoring leader's performance. Some programs discourage SLs from sending positive feedback (it is seen as a waste of production time), so most interactions you will have with an SL are in the form of negative feedback. Scheduling is done in a way that best suits the program's turn-around time. It is expedient for ETS to have a very large rater pool that can score an administration in a couple of days rather than a smaller, more experienced group of regular raters who can work more carefully and accurately over the course of a week. As a result, hours are inconsistent, and shifts are frequently shortened or canceled once an administration is finished.