A great tactician, and the one most often compared to Grant (of whom I have mixed thoughts previously posted).
However, Lee lost the war for the South. By committing so many resources for so long to the defense of Virginia, the rest of the Confederacy was relegated to begging.
Sure, Virginia was critical to the Confederacy and deserved more resources in its defense than, say, Arkansas. But any rational overall commander would have redeployed forces to defend Atlanta, or to liberate New Orleans -- the gateway to the Mississippi.
Lee was a general not of the Confederacy, but a general of Virginia -- first, last and always. In doing so, and being blinded by state patriotism, he doomed the Confederacy (and by association Virginia) to defeat.
In modern parlance, Lee never got the big picture. Any comparison of Lee against Grant needs to take this into account -- and by my reckoning a high ranking general who fails the grand strategy test fails as a high ranking general. Lee would have made a damn fine corps commander -- but he exerted influence on the Confederate approach to the war far in excess of his capabilites.