Yes!!! but in personal life I think if you really like someone it does not make much difference although I suspect it would be a problem if the "fit" between the partners was totally off. For example a really tight vagina and a huge penis, or a small-average penis and a looser vagina. But in most cases I think nature makes things fit pretty well! Women can do medically tried and tested exercises to tighten up the vagina but I don't think there is much a man can do to enlarge his penis. There are other ways to have intimacy I guess.
Yeah I agree it works totally different in personal relationships. The sex can be more spontaneous, the penetration can be spontaneous as well, sensing the girl's wetness and gradually increasing depth as her juice flows. That can even make more of a difference than size mismatch. I suppose a good girth gives a woman a greater feeling of 'fullness' - and may also be handy for riding her clit along lengthways. A good length can, with certain positions, sometime help to stimulate her g-spot. A big mismatch is when the woman's internal channel is just too damn short. This can happen especially with some Asian ladies who are built almost to scale (I'd find myself demanding I.D frequently till I realised they were late twenties). In those cases, the man has to proceed to enter with caution. Similarly, if the woman is not well lubricated. But that brings me to one of my personal bug-bears - too much lube.
If a man enters slowly, it is often possible to feel the small hot jets of a woman's natural lubrication, almost like traffic light encouraging him. There's a great bonding ion the physical level when that happens. It's one of the reasons I like the super-sensitive, think condoms such as Skyns, and also makes me feel fortunate to be uncircumcised and so naturally sensitive.