Initial reactions to the Nexus 9 have been less than stellar, to say the least. In David Ruddock's review, one of many sour points for the hardware was the volume and power buttons:
...the volume rocker and power buttons on the Nexus 9, for example, are simply bad. They're squishy, have almost no travel, and provide very little feedback unless you know the exact angle to hit them at.
It looks like manufacturer HTC may be addressing at least some of the problems with the initial batch of tablets, its first since the HTC Jetstream way back in 2011.