I'm on a very low dose of lisdexamfetamine and i freaking haaaaate missing a dose. As I understand it, it is a precursor of dextroamphetamine and your body converts it into it slowly through a metabolic-like process-- so pretty similar to XR but less of a saw-tooth curve throughout the day and more of a single sine curve. I wouldn't call it a nightmare, but it sometimes feels like one. It is really a miracle drug for me in terms of letting me let myself comply to external demands on my attention and order my life.