Darkvision really has no impact at all. I'd rather take a random resistance, so Dragonborn resistance wins over darkvision.

The breath weapon is a wasted action that could have been spent doing something more powerful. So that's a minus in the Dragonborn column.

They are worse than some other races, but... Are you going to have any problems keeping up with the difficulty scaling because you picked Dragonborn over Half-orc? Certainly not!