It is what it is: a staffing agency.
As a casual - other casuals will get paid more for doing the same job as you, other casuals will get paid for travel and you may not, calls for work are inconsistent and at the last minute, if you are booked to work and turn up and they no longer need you you will likely not get paid for your travel, effort and punctuality. Unprofessional at times.
Every time they call you for work, it's like they are twisting your arm to get you to go out and work for them so they can earn their commission. It's not an offer for work, it's a guilt trip.
As a permanent - there is a blurry line between talking about issues with Sugarman or the actual company that hires you, the communication between you, the hiring consultant and the company that may hire you is poor and miscommunication is common.
They make thousands of dollars when they place you with a company as a permanent full time teacher. They exaggerate, tell lies, do the whole sales pitch thing to make money from you. This can be good if you are desperate for a job but it is bad if you want a job that is sustainable and has a good culture.
It can be easy to get work
Travel, they don't listen to what you want