I took it for a year, it made me feel like a junkie. I'd "get lots done" like once a week, for 36 hours straight, and then spend the rest of the week feeling sleep deprived until ~fridayish, when I'd pass out until Saturday afternoon and "get lots done" again. I never wanted to go to bed, when I was on it regularly, but I never wanted to sit still, either.
For most of that, I took 30mg 2x daily, but there was a ~3 mo period where I'd rail 300mg in a day, then stay up for a week writing poetry and code. Crazy shit, I don't need that kind of "motivation" in my life, and the code I wrote was usually crap anyway, so the productivity was bunk.
Will stick to grass, it's much better at "fixing" my ADHD/short-attention-span/trouble-focusing/whatever-you'd-like-to-label-it. I never "get lots done" in 36 hrs anymore, but I don't lose a week to wandering around my town, strung out on addy at 3am, making friends with bums and exploring steam tunnels either. Any productivity I did gain on the pills was lost in the random shit I'd do during the come-down.