I have a few friends who take Modafinil and I agree that it does improve your cognitive skills. Not only does it help you stay organized and focused on your task but believe it or not it helps you in games too. Its almost like adderall dialed down a few bits really and boy did my friends skill increase during the use.

The only issue they told me they had was that if they took it after noon they couldn't sleep until the effect wore off.