I am student in Udacity's CS101 course and your observations are spot-on. In the past, I have used Khan, codeacademy, and watched the Intro to Comp. Sci. MIT OpenCourseWare lecture series - Udacity indeed does a superb job of combining the best elements of these learning platforms into one (for CS).
As a side, in paragraphs 7 and 13 you may wish to correct the course's length to most accurately reflect, 'seven weeks'. (source: http://www.udacity.com/overview/Course/cs101#tab-syllabus)