These were nice, but you had to configure each one yourself. I had one for google and youtube, but that was it. With DDG, the bangs come quite nicely preconfigured.
The main reason given for using DDG are privacy concerns with Google. Therefore sending every query to DDG's servers doesn't make sense to me. The redirect will be slower too than searching directly through your browser.
On the configuration side, that doesn't make sense either.
You configure it once and then because of Sync you get those configurations wherever you're using Firefox. And in Firefox at least it is easy - you just right click on a search input and select "Add Keyword for this Search". It's much, much faster than searching for the right bang in DDG, as those bangs aren't exactly obvious. And I only care about a couple of websites, less than a dozen, instead of hundreds.
Well, you should get a phone that doesn't restrict so much what you can do with it. Sending every query to DDG, even when you're not searching DDG is very problematic for privacy too.
Firefox on Android is pretty cool, being the only trustworthy browser that supports add-ons on smartphones right now, so I can use AdBlock Plus, HTTPS Everywhere and LastPass with it. It also has the Awesome Bar and does keyword searches as well, synced with my desktop Firefox of course.
I just received an iPhone 6 as a gift and while it's really cool, I quickly felt its limits and I sold it, because I couldn't see myself using it. Firefox is not available on iOS because of Apple's restrictions. VLC is also currently kicked out of the app store, by Apple of course, yet there are dozens of shitty apps available that violate its trademark, yet Apple doesn't kick those out. Dropbox on iOS, to have a working background process for backing up your photos, has to resort to dirty tricks like keeping location alive and triggering the background sync when detecting movement. There's non such thing as Tasker for Android. And the list can go on.
On the other hand, iOS has a far better privacy model than Android. I can deny apps specific permissions and don't have to accept a laundry list of them wholesale.
True, but it's not a solved problem because apps can keep asking ad-nauseam about wanted permissions and even refuse to work. For example Facebook's Messenger asks about being able to show notifications every time you open it, until you say Yes. For me personally it is much easier to not use apps that want unjustified permissions (for example I refuse to install Facebook's app and whenever I feel the need to checkout updates, I open the browser version which works fine).
Point taken though. Android's permissions model needs some serious improvements. I would also like to lie to an app. If it wants my contacts list, it could get a blank list, if it wants my location, it could get random coordinates in the middle of nowhere, etc...
Because of that, also, DDG is aware about every search that you do, even with bangs. Even though they allegedly don't do bad things with this data, it is a bit sad that you would ask one centralized service to route queries to providers in such a simple way, rather than do it client-side (and, say, have a mechanism to automatically install new bangs from the server to the client...).
On the configuration side, that doesn't make sense either.
You configure it once and then because of Sync you get those configurations wherever you're using Firefox. And in Firefox at least it is easy - you just right click on a search input and select "Add Keyword for this Search". It's much, much faster than searching for the right bang in DDG, as those bangs aren't exactly obvious. And I only care about a couple of websites, less than a dozen, instead of hundreds.