It depends on how you define "work". Apparently only 6% of first-time homebuyers cited the tax credit as the driver behind their purchasing decision. I suppose that's plausible, given low, low interest rates--which are a far greater contributor to affordability. But I'd be surprised if a majority didn't factor the tax credit into the price they paid . . . which itself could have helped the market clear in a lot of places. If your goal was to inject purchasing power into the economy, and help unlock the housing market, I suppose it worked, at least somewhat. If your goal was to help people afford houses, less so.
How to avoid working through lunch, and diseases related to social isolation.