Pros
It's a safe working environment where accommodation is provided, unless you work in Shanghai. You get paid on time and they offer to subside you some of your first pay when you arrive to cover living costs. You will, generally (see below), work with a professional team of double certified teachers (EF will pay for TEFL in some cases and require all teachers to later take a TKT YL exam). They offer additional benefits of a newly launched professional training scheme and opportunities to advance, with stipends for certain certificates in further education in the field of ESL if you are informed (again see below).
Cons
Staff generally are treated poorly, which reflects in their high turnover of both foreign and local staff. Local staff are particularly badly treated and not rewarded even though they work much harder than the international staff. Some foreign teachers that they hire shouldn't be training anyone let alone young learners and it is usually the excellent ones who leave very quickly. Most of the job is carried out on the weekends and evenings so if you like to have a good social life dream on. As an organisation it is all about the money they can make as they often cut corners when providing the correct materials a teacher needs including not informing teachers of, or paying for, extra benefits, holiday time or extra certification opportunities.