If anything, they'd have mixed feelings. With the bad, there's alot of good. Even in our struggling time, we're at the top and have achieved things none of them could have foreseen. People are too quick to say the founding fathers would be totally disappointed with the US at the moment. They would probably be impressed by some things, disappointed by others, and not surprised about a few problematic things that came to pass. But no one can really say in the end, I suppose.
If we went back to see America during its' early days, most wouldn't be too pleased either.
The USA of today is hell of a lot better than the one during their era.