Avalon English is probably one of the more reliable hagwon chains that I am know about. I worked for a franchise for a year and overall enjoyed my experience. The Korean teachers I worked with were great and very friendly and since I worked in a small school (only 3 foreign teachers and 4 Korean teachers) it made the year long experience a lot more enjoyable.
Day-to-Day: Work hours aren't bad, I worked usually 2-10, though at times that was stretched to 12-10:30p.m. depending on circumstances. I taught anywhere from 2-6 classes in a day (each 50 minutes long) for elementary & middle school school students. The work hours can be nice because it allows you to have your mornings while still being able to hang out and see people during the nights, which I enjoyed. Usually the first couple of hours are spent planning the days lessons and getting office work done; depending on your schedule that can vary from day to day.
Difficulties: Just like many hagwons and afterschool programs; Avalon isn't without its quirks. Communication can be very slow and difficult (language barrier aside), so at times that made meeting expectations and deadlines difficult as things weren't always communicated timely. There are times when tasks will be thrown at you and you are expected to finish it last minute (but that can be with any school, so not out of the ordinary).
Overall: Avalon can be a great place to work, always paid on time, very little hassle with money/insurance/end of the year bonus and often the Korean teachers and staff are extremely helpful and understanding. Avalon to me is a very reliable institute and I would feel most comfortable working with this large chain then some of the others out there. I enjoyed my experience very much.