Pros
One week off for New year and Golden week and another 10 days off (11 and more in subsequent contracts). Pay is always the same, independent of holidays or number of classes taught (pro or con...) You get a lot of non teaching hours that you can fill up with your own stuff, I tend to use the internet and study languages... You can leave the school if you like when you dont have office duties/teaching/cancelled classes. They provide a furnished apartment which is ready to move into and teachers usually have good support from Head Office/Managers/Japanese teachers when it comes to solving problems that arent directly school related. We get a percentage of the students tuition as a salary bonus. Private health insurance that covers 100% (never used it, so dont know if it really works). Students can be great, they have been in my experience.
Cons
Most teachers work Tuesday to Saturday, so they miss out on the (many) national holidays that land on a Monday. The 29.5 work hours isn't really true, you have to check in every day at 12 or 1 (earlier on Saturday) even if your first class is only 1,2,3,4,5... hours later. We can leave the school when we don't have classes, but usually teachers don't live near the school and going shopping is usually not very productive! 25 hours of teaching is usually respected, but try to remember most classes are 45 or 50 minutes long, thats would mean even if you have 30 classes a week you are not paid overtime, and get the same pay as other teachers who have 20. Teachers usually have classes until 9 or 10pm, so it's difficult to have dinner with family/friends.