The new tooltip style (on the dash) is very crisp and clear - dark transparent rounded rectangle background, white text and border.

The window titles that appear under the previews is not so crisp, the large rounded corners look out of place with everything else (excluding the search box perhaps). They are also hard to see against a dark wallpaper.

I suggest styling them the same as the tooltips, it will look more consistent and the white border will make them more visible against the background.