To a certain degree yes and no... I mean, like, well friendship-wise anyway, all my friends are the quiet type, and reserved - and I'm quite enthusiastic and most certainly not the quiet type lol, generally very opened etc. My best friend is very quiet and my ex is quite monotone a lot of the times, very reserved...
But all of us are very firm in our values and ideas and especially my ex who's quite blunt like me - and all of us are pretty smart (them two anyway, Cambridge student/student-to-be). We're all helpful and friendly and generally we're very caring towards each other etc, and we're quite honest about stuff.
So it depends on what the differences are exactly - some differences can make the relationship more interesting, or help it, like two chatty people put together wouldn't reeeeally work well, and neither would two very shy people - although those combinations probably do exist, but you know what I mean!