I am not a fan of the bike box.
It's fine when the cyclist passes stopped motorists on their curb side while they are stopped and gets in front of them before the light turns green.
But, the cyclist who is moving forward to the bike box when the light turns green is vulnerable to being hit by a driver who turns right or left (whichever side curb is on) when the light turns green. In the U.S. drivers aren't trained to look for a cyclist passing next to the curb before turning right on green.

There isn't a countdown timer on traffic lights for me to know when a red is about to change to green.