Well,
 Let me put this other way around. Microsoft and Yahoo merged together to grow as a big search engine and basically to compete with Google. Their (Bing, Yahoo and Google) main goal is to reach out maximum users and earn money via advertise. According to the market reports 2010, Google alone captures almost 63% internet marketing (numbers may be up and down little bit). Google is very innovative company which has changed everything in web search and internet marketing.

I don't know if you have used Google tools to monitor and analyze site but I have to do for my blog. I use tools from Google, Microsoft and Yahoo. Compared to Google, it seems like Bing and Yahoo are learning how to crawl and gather information from site, how to analyze web data and process them to reach out internet users.

My own experience:::

My site is not so heavy busy site but get decent traffic (About 10,000 page views) a month and 82% of it's traffic is from Google, 7% from Bing and 6% from Yahoo. It's not conclusion but it will not be over statement if I say people still prefer to use google than other search engines.

Just my thoughts and may not match with other's view.