Personally I prefer something a bit larger, but it truly does matter what you do with it. If you know how to please a woman with your fingers and tongue, and you know what positions make your cock feel bigger, then you're more than adequate. If you can toss in some quality dirty talk, that's even better. And yes, there is such a thing as a cock being too big. For most women, banging against their cervix is not a pleasant experience.