The negatives... administration can be difficult to deal with, 45 minute bus ride to Seoul (if that's even a negative).
The positives... EVERYTHING! I spent two years here and loved it completely. You are reliably paid (paid well) on time, the pay and benefits are through the government and much higher than the majority of jobs out there, the apartments are very livable, the staff are incredible.. it's a built in social network of about 100 foreigners and Korean colleagues who love to travel and explore, the curriculum is developed collaboratively and not stressful, there is no marking/grading on a consistent basis, there is a full gym within minutes from your apartment, the surrounding area is beautiful, it's MUCH cleaner than Seoul, I really can't say enough about how wonderful life is at EV. I suppose you can find fault with any job, city, insert-life-quips, but overall I think you would be hard pressed to find anything like this in Korea.