I have tried bing several months back, and had to revert to Google because of below average quality of search results (compared to G). However, this time, the results appear to be good (and some times better than Google), and have been using it as the primary Search Engine for the past one months.
Bing need to improve on:
Crawling fresh content: Though it improved over the past few months, it needs to improve further.
User interface: Many people don’t like background images. It diverts the attention from search. Also, the search box and font are very big, it can be a little smaller.
Google itself has lot to improve, and bing should think beyond Google. (anyways, Google is messed up after Panda, though it recovered to somel extent after feedback from several webmasters)
Anybody using blekko? It seems to be a decent search engine.
I think its good news for website owners. Google has a strong monopoly over search results. If you loose Google traffic you will loose your business. If you get traffic from other search engine like Bing, you will have some chance to survive when Google hit you.
Great point linkgenie, you want to make sure you are diversifying your traffic sources (google, bing, social media, etc.) as much as possible so all of your eggs are not in one basket. If one source delivers 75%+ of your traffic and that source goes away, then you are in trouble.