I've been using DDG intermittently for the past two years, and solidly (with fallbacks to other search engines) since June, 2013.

Overall the design looks decent. Remember: less is more.

I don't know if features were modified since fskc--off posted, but I'd agree strongly with both his primary concerns: ditch ALL fixed headers and footers, on ALL devices, and keep maximal contrast throughout the site. My eyes are no longer quite so young as they once were, and low contrast designs are bullshit. The "off-black on off-white" argument applies only to print materials, not online, where contrasts are inherently lower, and are worsened by increased ambient light.

I find the grey background on the focused search entry distracting. I've removed it. The outline is sufficient (if not excessive itself).

I find the font sizes in general too small. I prefer specifying fonts in points not pixels, and very, very strongly recommend that all text-oriented dimensions be either in ems or percentage of screen width. In general, don't size text elements if you can help it. I set an overall content width of between 45-50em for most sites, with a minimum 2em margin (and that's as a fallback). I apply my own CSS to many sites I visit, some 1000+ at present (yes, including HN, increasing contrast and font sizes being principle changes).

I notice the browser URL no longer reflects the present search. I dislike that change as I'll copy and paste search URLs fairly frequently. Please retain the previous behavior.

The search syntax icons on the RH side of the page underneath the "Spread DDG" link looked at first to me like social share link crap (another feature I strip from most sites). I'd suggest putting the "spread" link elsewhere and more clearly differentiating it from the actual search tools.

Of features missing on DDG which force me back to other sites, the lack of time-bounded search is probably the biggest (other than simply lacking expected search results). I've been impressed by the integration of OpenStreetMap results and would like to see similar type development, as well as your use of Wikipedia and similar informational sources in results.

Overall: fairly subtle changes, and gripes notwithstanding, not bad. That's actually high praise ;-)

Also: I'd very much like to thank you for actually previewing the design in advance of releasing it. While online services make drastic changes possible, they're not always welcome, and I feel far too many sites make the egregious error of dropping a new design on users with no warning.

For the "next.duckduckgo.com" site, I've got the following CSS tweaks presently applied. All but the last are legacy, some may no longer be strictly necessary:

#header_wrapper {
position: static;
}

#header_wrapper #header #header_content_wrapper #header_content #header_button_wrapper #header_button #header_button_menu_wrapper #header_button_menu {
z-index: 2;
}

#search_form {
font-size: 15pt;
}

.bang_suggestion:hover {
background-color: rgb(228,246, 255);
}

.bangwrap {
z-index: 2;
}

.snippet {
font-size: 14pt;
}

p, body p, li, body li, dt, body dt, dd, body dl {
font-size: 15pt;
}

.web-result:hover {
background: none;
background-color: inherit;
}