Falling Skies season 3 on the whole was disappointing, but the finale, "Brazil," may have been the biggest letdown.
After the build up of the Volm device and its supposed ability to save Earth from the Espheni, there wasn't much to it, especially after the attack in last Sunday night's episode. They dug the device out, transported it and get it ready all off-screen. That challenge would have been a more compelling hour than several of the dragged out episodes this past month. Instead, we saw the device activated, initially appear to fail and then the Espheni shield destroyed.