I have to say, why such loud mouseover effects? It's distracting to have all these boxes popping in and out as I scroll through the results. I get that you're trying to show that the click area is that big, but it impairs readability--most of the time while using a search engine I am reading very quickly. Perhaps some people leave their mouse off to the side when they scroll, but many people "think with their mouse," pointing at stuff as they look at it.
I would personally tone them down to just the underline appearing on the result link (where that activates for the big click area, and not just when mousing over the link within the big click area).
I'll agree that it's about the right contrast for keyboard navigation, but a compromise is straightforward: show it only after pressing j/k (as with the current behavior), and use a much subtler effect for mouse hover.
I don't mind it. I think the biggest problem is that it uses JavaScript. The small delay between hover and style change makes the site feel sluggish. Using the :hover pseudo class would be better, and is supported by all browsers other than IE6.
I definitely agree with this although I think you could lighten the shading and get away with the current method. The dark grey just creates too much of a contrast change for me to read it easily. It only adds a split second to my reading time, but it is noticeable.
I also don't really like the boxes/buttons at the top (they look very much like every other site trying to create a mickey mouse design), but this is probably just my natural resistance to change. I probably won't even notice in a week.
I changed to DDG a while back as my default search engine and must say that I've been extremely happy with it. To hear about an interface upgrade was initially a little upsetting as it brings to mind the recent changes to Google. The preview and instant search features are what finally pushed me to the simplicity of DDG. I'm glad you kept the same clean design and didn't try to change what already works wonderfully. Please keep up the great work.
I would personally tone them down to just the underline appearing on the result link (where that activates for the big click area, and not just when mousing over the link within the big click area).