Pros
Flexible schedule, although you are expected to be available Monday through Friday and some Saturdays. Shifts are short, around 6 hours, not unlike if you were working in retail. Not strenuous work. You're mostly seated but you get up often to escort candidates from their workstations and you are also responsible for cleaning and opening/closing the test center. There is a potential for good work/life balance if you aren't expecting this job to solely support you.
Cons
Your shift is often boring and dull. You're seated in front of some computer monitors and a glass window looking at the backs of people's heads. There are inconsistent hours available per week. Some months like June and July are busy whereas you're practically not even working that much during December and January. Not just that, but testing dates may get closed if not enough exams scheduled so your hours get cut. Some candidates who come in for their exams are high anxiety-prone or demanding and can act rudely.