I've never owned any myself but there are a few people around here that do. The only real complaint I've heard more than once is that they have had calving trouble in the past. The breed seems to be working on that recently.
Ryan, if memory serves me correctly, I believe Brown Swiss were derived from the Braunvieh breed, selected heavily for milk production, but I could be wrong.
There is a fairly large breeder about an hour or so from us that raises braunvieh and black angus cattle. I really like the looks of their straight braunvieh cattle, nice thick cattle. Their braunviehs appear quite calm and their angus are, well, angus. But some of the crosses I have seen come through their sale each year have had a major attitude problem. One in particular that comes to mind was a F1 that came out with tigerstripes. As a yearling bull, he cleaned the ring out and tried to tear up the trailer of the poor soul who purchased him. The outfit that sold him is very reputable in this area, but I've never bought anything from them, this being one of the main reasons. That animal belonged on a plate, not in a pasture.
cfpinz