It'll be good for a high school student, and it'll last you 4 years. But you'll be lucky to get $400 for it after 4 years time.
That said... $1200 is a lot of money to be spending as a high school student. Save it for college or a car. Trust me... I just graduated from college and wish I had saved more for college and had a car that wasn't 23 years old.
Why do you even need a laptop let alone a MacBook Pro for high school?
Any old laptop/desktop can do the powerpoints / term papers etc for high school.
Save the money up for college like seriously. I saved $3k up thanks to not buying much during my high school days and it helped pay off for those damn $100-200 textbook. Tuition is going to absolutely kill you with 4 years colleges running $20-30k+ per year. So why spend $1200 on a macbook when in 4 years you'll no doubt need a new one for college...??
Actually a laptop can be useful for high school. It is even encouraged in elementary schools, at least according from some fellow co-workers who have children in elementary school. Granted their children are attending "high end" public schools in semi-wealthy to wealthy communities. Lessons are actually taught using the laptop with e-book textbooks and classroom / homework assignments are e-mailed to the teacher.
Is this the case for the average inter-city public schools? Probably not. The necessity of a laptop seems to depends on demographics. Therefore, it is possible that a laptop is necessary for the OP.