Pros
Great money, quite an easy job once you're used to the teaching method, nice colleagues and no complaints about the holidays. The academy had a nice feel since it was not like the big offices in Madrid. Can be quite a lot of work if you are new to teaching but you learn a lot. The training is hard but really useful if you are interested in professional development. I rate the method; you act as more of a facilitator than a teacher to try and get students to speak as much as possible. Works especially well if you incorporate grammatical structures from outwith the student's comfort zone and include a mini presentation in every class to allow open conversation for a bit. I have spoken to people who don't like the method, which is fair enough - I would not expect consensus on what constitutes a good class. However, the teaching method genuinely brought about good student progress and the evaluations I got while at the academy were really positive.
Cons
I didn't really like the corporate feel of the offices in Madrid and it would probably have been a different experience there. I would not recommend an external job - loads of travelling between places and less job security (based on what I heard - not first hand experience). Apart from the difference between external and internal salaries, you get the same money no matter which city you are based in. So my advice is to go for an internal job in a small city, much better money in real terms for the same work - probably a nicer working environment too. The training is tough and it can be quite ruthless. Having said that, common sense seems something lost on a lot of people who have been moaning about their experience in the training. The business sells its teaching method due to the fact a lot of Spanish people feel that the way they were taught English in the past did not work. Vaughan Systems has made a lot of money based on the narrative that they offer a new approach. If you go into the office and criticize the key thing they have been selling for the last 30-odd years, you aren't going to get a job. Simples. One fair criticism of the method is that it becomes quite repetitive both for students and teachers. Two years at the company was enough for me.