The original Fire oddly lacked external volume controls, so you had to tap through the menus just to raise or lower the sound. (wired.com)
Some of those point at hardware issues that aren't addressable, such as the on / off switch placement making it easy to accidentally power down the tablet, and the lack of external volume controls, however it is expected that there will be many improvements to the general running and usability. (pocket-lint.com)
The Nook Tablet has external volume buttons for easy volume control; the Kindle Fire's volume is always controlled on the screen. (huffingtonpost.com)