I've taken Modafinil for over a year. I took it daily most of the time. I recently quit. Having now switched to racetams, I can tell you that I would pick a racetam over Modafinil any day of the week if my goal was cognitive improvement. I do not personally consider Modafinil/Armodafinil/Adrafinil a nootropic. I have a bottle full of Modafinil that I haven't touched in months and another full of Provigil. The only time I would consider taking it again is if I needed to stay up for an extended period of time because that's really the only advantage it gave me. I've taken it a few times to study for finals over a few days with no sleep at all. While it did a great job of keeping me awake, it did absolutely nothing to counter the effects of sleep deprivation. I still felt sleep deprived most of the time, I just wasn't fighting off sleep. Neither did I find that it improved cognition or memory at all. There was more focus while on it, but nothing I can't now get from a recetam stack without the nasty side effects. Your mileage may vary. I've heard that it's being studied as a treatment for ADD/ADHD, so it may have some use to you in that regard.
From my observation modafinil is NOT something that will allow anyone to pull off science-all-nighters.
It's good to counter caffeine dependency and fight day time sleepiness, but at high dosages (more than 100mg of modafinil or more than 75mg of armodafinil - for those of you who are healthy) can hinder understanding of abstract concepts.
It seems to me that I study best while on caffeine, but the effects are short lived and modafinil saves me from becoming and intellectual zombie before I recover for a next coffee trip.
It's not like modafinil doesn't have other benefits - as one meta study greatly summed it up - "it makes everything you do more bearable and more enjoyable"
Therefore I'm able to study longer, though not at full capacity as on caffeine, so I often try to mix both.
Important thing to notice here though, is that, coffee can really differ between one brand and another and for now I have no way to tell which one's better.