Ventajas
Flexible, easy to learn the basics and complete self-paced training, and a good option for side income that can work around a main job or busy life. They have a help line to call for trouble with jobs and questions. If you have to leave a voicemail, they are usually pretty good about calling back fairly quickly.
Desventajas
Sometimes you have to figure out how to do certain jobs on the fly if you haven't done them before, so it can feel a bit like being tossed in and expected to sink or swim. They do have a help line to call if you have trouble figuring it out, though.