You may ask what about Google Webmaster Tools? The answer is, its not among the best tools to check back links. Google only displays very limited number of backlinks that it has counted as a genuine link towards your site. Since Yahoo search is now powered by Bing. Therefore, Yahoo has suggested users to move over to Bing. But the fact remains that Bing is also not very good in indexing back links. Specially for small and niche websites.
How Bing’s Tool be used by webmasters will now needs to be seen. But a great tool that Yahoo Site Explorer was, will always be missed.