I was diagnosed ADHD before it became a fad, and I've gone through a number of different medications for the disorder. Every one affected my ADHD in distinctly different ways. and Ritalin in particular did exactly what the comic describes. (Productivity at the expense of creativity.)

The three that had any sort of effect were Ritalin, Strattera, and Adderall.

* Ritalin was robot mode. I'd get work done, but only in areas that were analytical, not creative. Off the Ritalin, my problem with creative writing was being easily distracted and procrastination, but my papers were (reported as being) entertaining with a sense of "flow". On the Ritalin, I was so analytical that my teachers started accusing me of plagarism, because it looked like I was writing for an encyclopedia.

* Strattera: Strattera had very little effect on my concentration or procrastination. Where it had a dramatic effect was my impulse control; it inserted a short buffer of introspection between thought/desire and action that had sometimes been missing. Off the Strattera, I'd buy a box of cookies I'd never tried before, because they looked interesting; no second thoughts would emerge at all. On the Strattera, I would think that I didn't need the calories, they were just a different arrangement of chocolate and biscuit, and a waste of money in any case. Didn't help with my schoolwork, but it did have a very positive effect. (Especially on my diet and my entertainment budget.)

* Adderall: Adderall is what I use now. It gives me extremely intense focus on whatever I am doing, without reducing my enthusiasm for the task or my level of creativity. The primary downside is that it allows that focus on anything I'm doing when it kicks in. If I'm doing the dishes when it starts to work, I'll do all the dishes, then clean the kitchen, reorganize the cupboards, clean the fridge, and only then start working. My tactic is to take the pill with my coffee, set a timer for 1 hour and play some casual games, then start on a problem for my job. When it kicks in, I'll be set. Adderall is notably different in SR and XR varieties as well; SR is a short intense spike that lasts 2-4 hours, whereas XR works after an hour and a half and keeps rolling for 5-9 hours, depending on food/caffeine intake.