Does the Kindle Fire have serious usability issues?

A summary of Nielsen Norman Group's tests said the Kindle Fire "offers a disappointingly poor user experience," and cites the size of the screen as the main culprit.

Then the group adds this caveat: "This was a small study, with only four users, but qualitative studies often generate deeper insights than bigger, more metrics-focused quantitative studies." The link to the findings first appeared on Daring Fireball. 

Highlights of Nielsen Norman Group findings:

• Small: "Everything is much too small on the screen."
• Errors: "Frequent tap errors and accidental activation."
• Heavy: "Heavy object. It's unpleasant to hold for extended periods of time."
• Slow: "Scrolling can feel erratic...huge lag in response after pressing command-buttons."
• Apps inefficient: "Using apps...is less efficient...because it lacks physical buttons."