Pros
Hours are flexible. They will work around your availability. Generally friendly management. Generally friendly co-workers. Most kids are well-behaved and fun to talk with.
Cons
High frequency of student cancellations, resulting in pay cuts. No income security. Disorganized atmosphere - I applied to work at the center close to my house but was repeatedly scheduled at the one across town for several weeks. False advertising - was told in the interview I would get paid for last-minute cancellations, but this was not the case. Too many teachers - hard enough to get hours, let alone when kids didn't show up. Restrictive curriculum leads to a lot of repetition in lessons, which quickly becomes dull. Subject tutoring pays less than ACT prep, even though the workload is comparable.