Salary is 8000RMB pm and 1500RMB pm during summer and winter vacation periods. 5000 flight reimbursement. Free furnished apartment (unshared I assume). 200 pm utility allowance.

Get off your high horse, Hammer! Spare a thought for your Chinese colleagues - they're on at most 3,000 RMB/month plus having to live in a room + sharing cooking facilities. Your offer is well above the average for 20 classes/week without office hours. The only problem is you might have to teach well to justify your relatively high local salary. If you can't do that, your services might well be dispensed with sooner than you expect. In China, students hold the power regarding that. If they dislike you, you'll be on yer bike after a month or two! If you have no teaching assistant, you'll be faced with discipline problems in some of your classes, another thing to be wary of.

Personally, I wouldn't teach middle school without a Chinese teaching assistant. She will keep you from becoming unpopular by advising you how to come across in class, and will deal well with the discipline, saving you unnecessary hassle.

Unlike you, I have taught middle school for a Chinese agent who supplied me with a teaching assistant, for 5,000 RMB/ month plus most of the perks you mention, and I was never skint at the end of a month. I was posted in the sticks, the cost of living was low, the locals were friendly, and life was at a slow pace.