Create your own schedule.
Various opportunities to accept long-term positions.
Pay increase with acceptance of long-term job.
Can be assigned to multiple districts. (I had 6)
The ability to work in whatever grade level and subject.
Most teachers in the schools are more than willing to help you out if needed.
Cons
Depending on the district there might not be very many jobs open.
Some schools give you the option to work as "Teacher Coverage" which means they'll put you wherever they need you. Sometimes I ended up sitting in the office for hours doing nothing.
Depending on the school and your personality the kids behavior can be pretty difficult to deal with at times.
No summer work.