I honestly love the left hand sidebar features, specially for link building those can help you find goldmine if you are not good with advance queries.

However, I have no stats or any research to tell you about the traffic portion of those filters. My guess is not a lot of people use it. That is why they have now added a realtime search feature.

This is also a guess, or a hint of an idea on how to quantify this - however roughly.

When you look in your query terms stats inside Webmaster Tools, you notice that you get some impressions at a wildly different position than the norm. I'm assuming that some part of those impressions comes from Search Options being used. So that number would be the ceiling number - the maximum. In reality, there are several other reasons you might get a wildly different ranking, so the true number of search options users is going to be lower.

[edited by: tedster at 1:58 am (utc) on Aug 27, 2010]

I never use it.