I'd say Reagan's term was a failure. He retreated on taxes, Iran-Contra, and basically slept through the term. I love the guy but the truth is his second term was largely a failure.
With all due respect, in his second term he passed the major tax reform bill that resulted in fewer tax brackets in return for eliminating most tax shelters. That was the closest we came to a flat tax. Also, he gave the "tear down that wall" speech. I just don't see the failure.