I did my CELTA in the UK with International House and they seemed great.
You do hear some bad stories. I was in Japan for the first two years after taking my CELTA - that is, until a few weeks ago - and there were a huge number of complaints about most of the big schools.
I worked for one of those big schools, and can say that the complaints are true to some extent. Most foreign teachers of English in Japan have no teaching qualification, get no real training and little support on the job, and can be under a lot of pressure to maintain the financial viability of their school in a steadily declining industry.
Sometimes, though, you get the feeling that the teachers simply didn't anticipate having to work hard in a responsible job, rather than getting a nice, easy working holiday. Sometimes, the complaints your hear from the teachers are down to them not acting especially mature or realistic, or failing to communicate or understand that Japanese culture is simply not the same as that of wherever they come from.
Also be aware that a lot of people vent online, and that doesn't necessarily represent the balance of their experience.
Then again, I have read about companies in some countries that seem to be out to rip you off/screw you over, pure and simple.
My experience of working in Japan, for two different companies over two years, is pretty mixed. My immediate colleagues and students were fantastic; the higher levels of management somewhat lacking in competence and people skills.
I love the teaching and in no way regret not doing the PGCE. Maybe that's something I'll return to one day. Then again, within EFL, I can continue to teach, do my DELTA, then potentially move towards teacher training and/or school management. One day, I'd like to do a masters in something to do with EFL and possibly go into the more academic side of the field. There's a lot of possibility.
If you do the PGCE, you'll probably be doing less pure teaching. More of your job will be about managing the classroom environment to ensure learning is taking place at all. So even though less learning might go on in your classroom, you'll potentially play a more important role in the development of young people as human beings. You might be the inspiration they need in life. My cousin has been teaching in an educationally low-achieving part of Hackney, east London, for a few years now, and loves that aspect of the job.
Going back to EFL, there are bad schools and there are great schools. With some research, you should be able to find somewhere you'd be happy. Once you get into a country and start to learn the language and gain more experience of the place, you'll be able to find out much more about other good schools in the area.
If you want to teach EFL in a language school, look into International House for your CELTA. Study with them and get a good pass, and they might hire you to work in one of their schools right after qualifying.
International schools teaching a national curriculum probably pay better and might give you more holiday and benefits.