It's atrocious. No slider, clicking on it "blips" the speakers so you can hear how loud it is. You have to hover pointer on top of it which enlarges the green circle by about 10% to show "Hey, you're hovering me, in case you missed it!" and then scroll so the the tiny tiny dot gets slightly more enlarged (which clearly indicates new volume, duh). Then it shrinks to a smaller size back when stopping the hover.
Oh, the arrow to the right? Does that open the customary volume slider? No that's the sound device picker. Speaker to the left is the mute. To make matters worse it's in the same "group" as the network symbol is (although there's no network settings when clicking), and sometimes clicking the thing doesn't work at all, depends on how much explorer.exe decides to hang at the moment.
But surely I just got some broken alpha/beta version.