I think one of the good things that comes from the sprint relay is that you are rooting for your team. Not your men's team, not your women's team, but your team. The current format requires relative depth in a country's men and women to perform well, and, maybe that just favors the perennial winners, but I really enjoyed rooting for the mixed teams. It was exciting, and fun to watch.
Only complaint from the arena was that the screens needed to be 6 or so feet higher. They were low enough that unless you were up against the railing the view was blocked by umbrellas.