Pros
When I first started, they sent me temporary jobs constantly. More than I was even able to accept. Flexible — you can send in your availability and turn down any job offers that don't match it without penalty.
Cons
Low pay — most temporary jobs are minimum wage. This was not the case when I first started working with Atrium in 2015. I gave my recruiter negative feedback about a week-long job in which a very rude employee of the client (who was not my supervisor) screamed at me for several minutes for following the instructions of my supervisor (who was also her boss). After this, I suddenly went from working 30-40 hours/week with Atrium to about 8-15 hours/month. After several months of this, I got an email from my recruiter saying they were dropping me.