For example: I don't see any advantage in those search bangs, simply searching "shoes amazon" on google will do the job, or if I really want to search a specific site one can easily do "shoes site: amazon.com", and considering all the other things google can do...
duckduckgo might do some of those things, some of those even well, but I don't know, therefore the question about a detailed comparison... in google:
search literally by using quotation marks "to be or not to be", show weather, stocks, definitions, times, calculate anything, you can even do stuff like "notebook 200$..300$" which searches in that specific price range, currency and number conversion, exclude some search terms, flight information and lots more... whenever I read of something about supposedly awesome duckduckgo-features, it seems like the author(s) don't know a lot about google's capabilities... or I guess don't mention it on purpose. Many don't know about google's capabilities I guess, and then they might go "look what duckduckgo can do", ehm "google has been capable of that for x years"...
and by the way: last I checked google was immensely superior in search term results (even without the bubbling effect)