I wish I could be excited about the decision - it does give me what I want - but I'm not.
The lawyers are all over the tactical issues (is the decision too monolithic? Will it risk having a conservative Supreme Court establish precedents that will make achieving gay marriage harder?); let me take one social/political one on.
I don't want this to be Roe v. Wade. That decision arguably 'settled' the abortion issue, but in reality, it pulled a half-baked cake out of the oven and put it in front of the polity.
The law and social values must interact closely; at times each tugs the other forward or backward. Where they move in rough concert we get massive, successful social changes - suffrage, civil rights, improved rights for women. I tend to think that Roe v. Wade pulled them a little too far apart - which is why the issue of abortion remains so curdled and poisonous today.
I want gay marriage to happen, and faster, please. But once it happens, I want it to be widely accepted - a tranquil part of our social order, not a scab that everyone keeps picking at.
So yes, I'm happy that the court has made a decision for marriage. And I'm also sad that they have, because this needs to come from the political process, not the courts.