This job is basically for those looking for days OFF to have a better lifestyle, not money. You can make it up to 13 days off in a row + travel days (normally 3).
Then you will have to pay back the extra 2 you used per month. Its simple. If you had good savings thanks to your organized finances and investments previously, 12.9k plus 1k per diem per month, its quite good. If you want only money, go to China.
KE is the best communting on earth. Business class travel, days OFF when requested and never even questioned, airplanes in wonderful shape, easy and very relaxed operation (excluding OE, which for me was super nice but for other might be stressing). After OE, you are on your own. 65-70 hrs average a month.
As a former EK slave, Korean is heaven.