Pros
Often great pay, set your own schedule (work as much or as little as you want), sometimes the work is really interesting and fun
Cons
Opacity, no interactions with humans beyond a messaging option on their website. They're so secretive that they don't even tell you a headquarters location! They only pay through Paypal, which can be a nightmare if you have problems with your Paypal Account. The assessments (necessary for joining individual projects) are often unpaid. Sometimes the work is tedious. Here's what they're most famous for: If/when they let you go, there's no transparency. You'll just go to log in one day, and it will tell you that you can't work. It's hard to prevent that from happening because they don't give you any feedback on the quality of your work.