The iPhone had guided tours when it launched. The iPad didn’t: you already knew how to use it. Unlike the iPad, it’s an open question as to whether users will be able to grok the Watch’s new interface paradigms.
Speaking of new paradigms, I spotted this interaction in the first video. In the Calendar app, the title of the page doubles up as the table section header. This is a clever, efficient use of limited screen space. As the user scrolls the table, the new header pushes the previous header upwards, like tables in iOS. Neat.