If you look at Reagan's promises and what he accomplished, it was a failure. Everyone makes him out to be as some hero (or villain) who cut taxes and spending and the size of government, when in reality his tax cuts weren't all that big on net while he grew the size of government, including federal spending and deficits. The MASSIVE budget deficits Reagan instituted sapped national saving and investment, thereby greatly reducing economic growth. He did deregulate a little bit, but on net Carter deregulated MORE in one term than Reagan did in two.
On net, I'd say his Presidency was a failure. Clinton, a Democrat, managed to reduce the size of government as a percent of GDP more than Reagan, and that's just embarrassing.