I think that the United States' republic form a government a front for a quasi-democratic capitalistic dictatorship thanks to the power of the Executive Branch. This is because this branch has an extreme amount of power. I don't think our forefathers meant for it to have so much power. They can pretty much do whatever they want.
Since the Executive Branch wields so much power in the United States, the country's republic government isn't really what it seems. The country is a lot closer to a dictatorship than many people realize, but the Executive Branch wields the majority of power more often than not in real world practice.
The United States' republic form of government is somewhat a front for a capitalistic dictatorship. This is because of the power the Executive Branch (or the president) has. The president does have too much say in many issues. That is what a dictatorship is after all. The US has their checks and balances, but do the work???
There is much to be made about the expansion of the powers of the executive branch, but the US is still most definitely a republic - maybe too much so. The Federal government, ironically, is more expansive today than ever before, and yet this increase has led to a kind of hyper-localization, with a very limited big picture outlook.
The question strives to put labels on things and therefore stigmatize them, but the current level of power held by the executive does not create a dictatorship in it's current form. We're closer than we have been historically, admittedly, but this is due more to general stalematemanship and brinkmanship in the legislature and judiciary. If those two bodies were working properly there wouldn't be a worry over the President's power.