Controller works really well once you've done a bit of setup to configure it (using the extended crossbar, setting up targeting filters, arranging all your skills to suit the button locations, etc.) Though I haven't played KB/M on this particular game, I expect it's the same way in that it works great after you configure it to suit yourself. Though part of the reason people are more comfortable with whichever they started with is indeed just familiarity, I suspect that part of also comes from comparing a platform they've already tweaked and configured for optimal gameplay with a new system that's still set to its initial defaults.