Pros
I've worked for EF for a couple of years now, and I can say that they do do a lot of things well. I still remember when I first arrived in China, and the amount of support I got as a first time teacher, and first time traveler outside of the States. I still do get a lot of support and training, but sometimes the training is a bit too much - especially when your teaching schedule is hectic. The people are what makes the job, for me. There's lots of down to earth people, and I've made friends that I know I''l have for life, even when we all move on.
Cons
The teaching schedule can sometimes get a bit hectic, especially in the summer when the students are on holiday from their regular school (so that they all come to our school). The pay could improve somewhat, but you can still save money every month (I still send money back to pay for my student loan, can you believe).