I get the feeling that as user/hardware base with fresh installs increases there will be more notice of issues in the Dash (atm
They may range from obvious to subtle, generally decreased performance, graphics issues like solid colored icons, audio glitches, increased pulseaudio use, ect.
Also sometimes the 'bad' persists after the Dash is closed for a bit or longer..
Haven't quite put a finger on yet for most except some blatantly obvious like opening the Dash over an active window like a media player, progress bar, ect.
By far the worst I've seen is if using a static blur & opening over a media player playing a vid, though many different variations with all the blur options , none that good