Has the DDG user experience suffered? If so, how? I much prefer the redesign, and I'm not yet aware of having lost anything in the move.
Perhaps not for the most common case (just typing in search terms and viewing results). But it does break some important things, the most annoying one for me is that you cannot link to the JavaScript-infested result pages like the expanded image search results. How do you send someone the result of an image search ("images foo" does not even work all the time and it's not the expanded view)?
Visually, the contrast is worse now than it was before. While this may be "trendy", it does harm usability.
The default coloring of the old results page was much easier to look at, as well. It made it easier to differentiate between the different types of content.
The fixed red bar at the top is distracting and pointless.
The auto-suggest is also wasteful and unnecessary. I find it contrary to the simplicity that DDG used to offer.
Yes, they're relatively minor changes, but they add up to result in an experience that just isn't as good as the previous experience. These types of minor, but harmful, changes can build upon one another over time, amplifying their negative effect.
The auto-suggestions have helped improve my results a few times, particularly when I can't think of a bang.
The red bar and default coloring are probably a little more subjective, so I can understand that. I do hope changes don't accumulate to become more negative, but I find these changes to be largely pleasant.