I changed my default search engine on safari to DDG, am I happy, no but willing to give them a chance and also using other search sources(github) for my purposes
On mobile safari you can't change the search engine (that I know of), so I've switched to the Mercury browser which does allow me to use DDG. I'm actually quite happy with Mercury, it's a snappy little browser with a good feature set!
You can change the search engine if you liberate/jailbreak your device.