Answer the following question: Given the following passage  "Windows 8 was released to a mixed critical reception. Although reaction towards its performance improvements, security enhancements, and improved support for touchscreen devices was positive, the new user interface of the operating system was widely criticized for being potentially confusing and difficult to learn (especially when used with a keyboard and mouse instead of a touchscreen). Despite these shortcomings, 60 million Windows 8 licenses have been sold through January 2013, a number which included both upgrades and sales to OEMs for new PCs.",  answer the following question. Note that the answer is present within the text.  Question: What made the new user interfact more confusing and difficult to learn?
Answer:
when used with a keyboard and mouse