Similar experience. Expensive, and it has no generic version, and it made my daughter downright drowsy. She was competing in swimming this season, and doing really well before we tried it. On it, at the smallest dose, she was like the slow-motion of herself, and with extremely poor coordination.
It is supposed to help with impulse control -- perhaps because it slows all reactions, giving the brain enough time to process consequences. We did not see it. She was still a big puddle every time she heard a no.
Everything was far better when she went back to a simple stimulant (Ritalin LA).
Looking back, it felt like there was quite a bit of insistence from our provider to continue with it. I did not like the pressure, and it felt odd.
Simpler things seem to work better for us.