This drug is most commonly called Seroquel in the U.S., and it usually is prescribed along with a mood stabilizer such as lithium or Lamictal. It seems to be well-tolerated by many.
I am so glad to see your post. My daughter, age 15, started Seroquel one year ago, so I really don't know about long term use. But she has been, for the most part stable. She was having attitude and defiance issues here at home (but not at school), but the last two weeks have been great.
Knowing that you were 17 when you started and have stayed stable gives me great hope.