I have taught the HTDCH curriculum once, last spring, and I plan on using it again next semester.
My students were sophomores-seniors who completed one semester of the HTDP curriculum, through binary trees. We used HTDCH for the second semester, and we basically covered all parts of the book written by last spring.
This curriculum, I find, is a superb transition from Scheme to Java. My students were very successful in creating and implementing class hierarchies; the design process is a great help. With all the practice afforded by HTDCH, the students were comfortable in their understanding of inheritance and interfaces. Of course, list processing is natural and makes sense.
Those students who went on to take the year-long AP class with me have been very successful with the AP curriculum.