From what I've seen and heard, there are people who really are better off than they were 4 years ago. The Republicans seem to think the question itself will win the election (Hey, it worked for Reagan!), but I haven't seen much analysis of what the answer is likely to be.
So what groups of voters are better off?
Investors - the stock market has recovered nicely since its freefall in the fall of 2008. Boomer friends of mine saw their retirement investments decimated back then and have seen them recover since January, 2009.
Young people and their parents - People under 27 who can remain on their parents' health insurance are clearly better off, as are their parents who don't worry that an accident will wipe out their families' assets. In fact, I spoke with a lifelong Republican parent who told me she will vote for Obama and the Democrats because of that one issue. She said it's so important to her, nothing else matters. I doubt she is alone.
People with pre-existing conditions - My sister-in-law is one of these, and obviously now her insurance covers things it wouldn't before.
Home buyers - It's true that home owners are not better off. But the decline in house prices has allowed several of my friends to buy a house when they thought they might never be homeowners. Yeah, they're better off and they probably don't outnumber the owners who lost equity or lost their houses, but there is a segment of the population that's better off.
Small businesses - In January, 2009 it was virtually impossible to get a loan. Nobody was lending money for any reason. I've seen my small business customers able to get the loans they need for operating capital or expansion. And the interest rates are still low. Again, they can't be the only small businesses in the country with that experience.
Auto industry - We all know the auto industry is recovering and with it, jobs are coming back. Not enough to make up for the number of jobs lost, but some people are finding work who could not in January, 2009.
Iraq veterans - I think anyone who was serving in Iraq and is now home would probably think they're better off now.
There are probably other groups I haven't encountered in my slice of life. And there are enough of them that I have to wonder if the Republicans aren't shooting themselves in the foot when they ask the question "Are you better off than you were 4 years ago?" I suspect the answer is "yes" for a lot more Americans than they would like to believe.