The most substantiative arguments I've heard against the idea come from the angle of the tax being a regressive "punish the poor" item by being narrowly focused

The most substantiative arguments I've heard against the idea come from the angle of the tax being a regressive "punish the poor" item by being narrowly focused on the cheap added-sugar beverages, while exempting fruit juice and other equivalently concentrated forms. For the populists in the crowd, this is seen as a way to make this particular vice a privileged luxury. Regardless, I'm going to vote yes; it really should be a luxury, we made a mistake back when we let it become a default option.