From a morale standpoint, I will not argue that Gettysburg was important, nor do I completely discount the effects of the victory had on the country. It certainly did. Perhaps I'm going too far understating it's significance, but it's merely because I feel Gettysburg has been overplayed.
That being that it's impact and significance have been, for too long, overstated (or overrated is perhaps the correct term) and the result being that the "glory" and "spectacle" of Gettysburg has eclipsed, unfairly and unrightly, the campaign that truly was the decisive campaign of the war, that being Grant's Vicksburg Campaign, and the resulting siege and fall of the city.
I disagree to some extent. Had the Confederates won the Battle of Gettysburg, they could have quickly moved through Maryland and into Washington, DC around the same time Vicksburg was falling. Having laid siege to Washington, DC (with the remnants of the Army of the Potomac in his wake) Lee would probably have forced Lincoln to negotiate some form of a settlement. Furthermore, despite the fact that the Union was carving up the west, a win at the battle of Gettysburg would have changed the complection of the war. Had the Confederates won the war, I believe that slavery would have been abolished (albeit years later than it was) and we would still have been one country today. Just my $.02...