In sheer numbers, it was a disappointment. According to polls, the country has turned against the war. Shouldn't you get more than 50,000 people in Washington?
Also, where were the politicians? Was any major presidential candidate there? The answer is no. Why not? Because the Democrats understand that these marchers are poison.
Contrast the anti-war demonstrations with the pro-life turnout. More people turned out against Roe v. Wade than the Iraq War.