Pros
I suppose flexible scheduling, but even that cuts both ways: just as raters submit their own personal availability, ETS often cancels or reduces shifts at the last moment, meaning you don't get paid.
Cons
The pay is pathetic and it has not even gone up to match the pace of inflation, which means that experienced raters do more work, more efficiently, for less money. The contempt this company has for its employees is further shown by the few emails it sends to them, which detail changes in company policies that, what do ya know, always benefit the bottom line (increased work quotas, decreased compensation for shifts that ETS cancels, etc). At this point, I'm actively rooting for the company to go out of business, as I will then be forced to look for other part-time work, which I would have done long ago if it weren't for life circumstances.