I feel like there's way too much sensationalism and hyperbole going on here, which makes me wonder how many of those who commented have actually taken this medication or are educated on the topic enough to speak from a place of knowledge.
People with narcolepsy take modafinil every single day and don't go into renal failure or end up in the hospital (at least it's not a common occurrence with this medication).
Modafinil isn't some research chemical only approved for usage in mice; it's been FDA approved for years now and has a fairly safe side effect profile. I actually had it prescribed to me for a while, and my doc said it's a better option than adderall/ritalin/amphetamines (which are also fairly safe if used as directed). Obviously the abusing of any medication can cause problems, so I'm only speaking here about using the medication properly.
As for the effect of modafinil, I did notice a perceptible difference from my baseline when I would take it. However, I think it's crucial to look at what else is going on in your life and what your baseline mental state is without the drug in your system. If you're already a lazy, unmotivated person with no drive to succeed, then it's not going to do shit for you.
Just like taking a pre-workout supplement is going to be futile if you're not someone who already goes to the gym; but take someone who works out consistently, eats right, and gets enough sleep for recovery, then have them add in a quality pre-workout, and it may take their performance to a higher level.
While on the subject of working out, to me that is by far the most potent "nootropic" available. And it's 100% natural and free. Not to mention the multifactorial benefits and how it improves every aspect of your life. No drug even comes close to the way I feel not only after a workout, but throughout the entire day when I'm in the gym consistently. I'm far more productive as a result of that daily habit.
Also if you're a male, get your testosterone levels checked. I've been on TRT for several years now (my levels were genuinely low for being in my 20s), and the amount of physical AND cognitive improvement I felt when it kicked in was precipitous. It was truly like night and day, and I had no idea what I was missing out on until I felt what it was like to have test levels at the upper end of normal instead of the low end. And I should mention that there's a massive difference with being on a medical dose of TRT versus someone who is on a "steroid cycle" dose. You have to be in the correct range; having low levels of test is unhealthy and negatively affects quality of life, but going too far and taking supra-physiological doses can be unhealthy too. TRT is "just right", perfectly safe, and has many health benefits.
So to recapitulate, modafinil can absolutely be a cognitive enhancer and make you more productive. But before adding in that variable, you have to get the rest of your life in order: get enough sleep every night, consume a nutritious diet, work out at least 5 days a week and do some light physical activity on your off days, get your bloodwork checked and correct any pre-existing health problems or nutrient deficiencies, and then after all of that if you still want to bring your performance up a level, you can add in the modafinil or adderall or whatever you like.