Depends on a lot of things. My impressions are mostly grounded in the research done by PEW, and they show some significant variations across demographics. Women, for example, are in general more "religious/spiritual" than men. People in the younger demographics (i.e. Millenials) also are generally less connected to religion than older age demographics (i.e., Baby Boomers). African Americans are shown to be more religious than other racial groups. As you'd expect, religious sects that encourage fanaticism (i.e. Evangelicals) as a norm will rank importance and interest above those that don't (i.e. Buddhists). There are geographic disparities, with the southeastern US (Bible Belt) showing greater reported importance on religion than other regions.
Overall, most (as in >50%) rank religion as "important" or "very important" in the United States. It may even be a clean majority (>66%), but I'm not as sure about that off the top of my head (it definitely is in the Bible Belt, though). Trends in other parts of the world may not be the same; I'm pretty sure the EU ranks lower on these kinds of surveys than the US; no idea about other areas as I've never seen any stats on it.
But I think it's important to point out that there are always some problems with surveys like this. They're self-reported, so you're relying on the subject's say so. Religion is often (or supposed to be) a way of life. When it is, one may overlook its importance because it's so much a part of who you are you don't really think about it. If other measures of religiosity are attempted, you run into the problem of how to do it. Sometimes they use attendance at religious services, but not all religions center around that. We do the best we can in measuring these things and must always keep in mind the limitations.