I think Citizens United will eventually be undone on principle (corporations are not people, money is not free speech). I see this on a long timeline: basically, we're waiting for Alito/Scalia/Thomas/allies to become the minority. But the law is too offensively absurd and contrary to common sense to survive indefinitely. The justices supposedly aren't swayed by popular opinion, but the court will change over time and CU will be revisited.
Meantime, it just lost its big scary teeth on the national level. All the big money in the world couldn't make up for the fact the Rs and Romney ran an imcompetent campaign and those who thought a deluge of scattershot advertising was stronger than carefully tailored and targeted messages aimed at particular potential voters were wrong. Also wrong were true-believers who thought well-conducted polling belonged in the junk science category along with climate change, and those who thought saying something enough times made it true.
Next time will be different, since nothing says even today's antiquated Republican Party can't reinvent itself, and the people with all that money might be stubborn, but they aren't dumb.
But for now, the message is that rivers of money aren't enough to make up for a world-view based on denial.
In Wisconsin, the Democrats need to up their game and catch up to the national party. They're still trying to run on reason, niceness, and unions -- all of which are just fine on their own. To regain the governorship and at least one house of the legislature, though, we need to make a few changes to counter that deluge of money. The events of 2011-2012 in Wisconsin show what happens if Democrats stay old-school instead of going with the best technology and science available.
Big money beats a poor game but loses to a great game -- that's where we stand right now. So the present effect of CU is to nudge -- no, make that require -- state Democrats to get competitive. To the extent you think the Obama administration and the national Democratic party are a force for good, CU is (for now) a good thing for national politics.
It's another example where those who try to resist change and cling to old ways will get left behind. I think CU is junk law, if that's a term, but that doesn't mean we can't work with it.