This is exactly correct. Excluding poor local search results (which is understandable bc of the privacy aspect), Bing/DDG has trouble with long tale search query relevance (5+ word queries), and also finding results from small or obscure sites. The later is simply because Bing's organic index is not as large as Googles.

Bing/DDG's organic results are still very good, but they are not as good as Google's in the above specific circumstances.