It happens to me 5% of the time : if the results are not what you expect, you can still ask DuckDuckGo to use google, just add !g to your search (or !gm for Google Maps, or !yc for Hacker News etc.) So userful!
More here : https://duckduckgo.com/bang
Yes. This makes ddg useful as a default search engine even if you decide that you always want to use Google Search, because that you can use all the other bangs.
Being able to search "on the fly" wikipedia, youtube, google maps etc. is very valuable
I find that it still falls down with a lot of programming questions, but in those cases I can always punt out to google. Aside from that, I think it works plenty well.
I use it as a primary search engine on all devices. Every now and then I'd fallback to !g or !gi if a particular search is particularly bad, typically to learn that Google isn't much better. But the fact those commands are there makes it super low friction :)