I've found DDG to be better at finding obscure content, and the Goog to be better at finding what I call "canonical" content.
For example, if I search for "binary tree" I probably want Wikipedia followed maybe by StackExchange. Google does that, while DDG sends me deep into the netherworld.
One awesome thing about DDG is their !bang searches. It won't automate an unknown search, but if you know the first thing you're going to want is the Wikipedia entry you just search ["binary tree" !w]; for related StackExchange questions ["binary tree" !so]; you can even do a straight goggle search ["binary tree" !g]. For the available !bangs check out - https://duckduckgo.com/bang.html
You don't need DDG for that, when you can use Firefox (or Chrome).
All you need to do on a website with a search box is to right-click on that search box -> Add Keyword for this Search... and then add a shortcut.
The cool thing about it is that it is extensible. You don't need to settle for the fixed "bangs" that DDG provides. For example, I have a "dex" shortcut for searching an online dictionary of my native language.
Also, it takes less time to add a shortcut of interest than it is to read the DDG documentation page to find out the right bang for you.
If you care about privacy, then this is also a no-brainer, since you don't go through a third-party server anymore.
I have my Firefox url bar set to DDG, so it's way faster for me to:
1. type ["binary tree" !w] in the url bar
than it is to:
1. type [wikipedia] in the url bar (I don't even know if it's a com or org, but DDG would be fine with just [wikipedia]. If I knew whether it was com or org, then I could skip the next step.)
2. click the wikipedia link in the now displayed DDG results
3. find the field to enter the site-specific search terms (for many -- but not all -- it's in the upper right corner)
4. type ["binary tree"] in the site-specific search box
1. Start to type wikipedia
2. Hit tab as soon as wikipedia.org is the first choice
3. Start typing the query and note that the suggestions are coming from Wikipedia, not google
Significantly faster than waiting several seconds for DDG to redirect
1) Wikipedia (in featured box),
2,3) Some Exchange/Notes migration software called "Binary Tree" that owns binarytree.com,
4) cslibrary.stanford.edu on binary trees w/exercises,
5) "Binary Trees in C++" from cprogramming.com,
6) "Binary Tree" at dictionary.reference.com, and
7) "Binary Tree" on mathworld.wolfram.com
You've got to admit that 2 and 3 are pretty glaringly bad in this case. My fold ends halfway through 5. Half of the top 4 links are for the data structure, half for some irrelevant company, so DDG is effectively placing this company on par with the data structure. If you didn't know quite what you were looking for in advance, this could lead to serious confusion.
Yeah, sadly that happens sometimes. I revert to Google (with bang syntax) when I am looking for something programming related and want a lot of results from stackoverflow. However, DDG is definitely better at finding some things. I recently searched for gentoo+postgresql related stuff and got highly relevant results, which weren't in Google's SERP.
For example, if I search for "binary tree" I probably want Wikipedia followed maybe by StackExchange. Google does that, while DDG sends me deep into the netherworld.