In his memoir Thirty Years' View,Thomas H. Benton, one of Gaillard's contemporaries, described him thus:
Urbane in his manners, amiable in temper, scrupulously impartial, uniting absolute firmness of purpose with the greatest gentleness of manners—such were the qualifications which commended him to the presidency of the senate. There was probably not an instance of disorder or a disagreeable scene in the chamber during his long-continued presidency. He classed democratically, but was as much the favorite of one side of the house as of the other, and that in the high party times of the war with Great Britain, which so much exasperated party spirit.