Depends, really. There really isn't a yes or no answer to these questions.
Some of the things they came up with were great. The Bill of Rights that was protected by a government structure that would be near impossible to infringe upon was their greatest achievement, in my opinion. The Monroe Doctrine, though it gets a lot of flak at times, was also important, and still stands today as a declaration of sovereignty. I also really like the ideals of a non-intrusive, representative government that is seemingly nonexistent today.
However, there are things that would never hold up in modern days. Washington's desire for isolationism was great when we were only 13 colonies on a vast continent. Today, with a population of over 300,000,000, that's just not feasible. Especially now that we're locked into a global economy. Slavery is also an unavoidable issue that should have never been. It denied the rights of men based on the view people of color were little more than property. A view I strongly disagree with, and one that does not match the intent of the Constitution. I also have to strongly disagree with the federalist movement. I strongly believe that a confederation (not to be confused with the CSA) would have been more in tune with the ideal of freedom. Federalists put the entire nation under the rule of a singular government, whereas a confederacy would have ensured state rights, by allowing a 'loose union', in which each individual state retains it's sovereignty, and chooses what is best for her people. No FBI, no CIA, no DEA, telling states what they can and cannot do, even if such a thing would be beneficial to the states people. Examples being DOMA, and the DEA's persistent refusal to acknowledge marijuana as having any medical benefit.
All in all, their intent was good, but once the voice f the prohibitionists, and the warhawks became louder than the voice of reason, it was curtains for the free, representative government that was once enjoyed.