After teaching for a number of years in China, and having very recently arrived in Korea, and without having any real information regarding your job offer, I think I can safely say yes, it's probably "too good to be true." International ESL jobs are a great source of disappointment(s) and frustration, at best. Believing I was coming into an improved situation was rather foolish notion. The things that were bad in China (for me) are better in Korea. The things that were good in China, are worse in Korea. It's always a trade-off, and loaded with compromise -- far more than you can possibly anticipate! Good luck to you.