The Nielsen Norman Group did a usability study on iPad apps not long after the device's debut in 2010. A year later, they've done a followup study to see how things fare today.
While most apps have made big strides in overall usability in the year since the iPad's debut, many of the apps covered in the study still had suboptimal user interfaces that in many cases seem to sacrifice ease of use in favor of good looks. Overall, the biggest UI problem present in the studied apps was inconsistent or obscure navigation controls.
