I'm a long time Qt user, and I always appreciated the delivered HTML help, but with 4.7 (I moved from 4.5.3 to 4.7 so I can not say about 4.6), I have often a hard time finding pages I know are there (at least they were in 4.5).
In general, the links from the "Home" Page are too sparse, and even in the sub pages, I often do not find quickly what I'm looking for. (Note: I use the plain HTML pages viewed in konqueror and I'm not using assistant).

E.g: In the chapter "Qt Desktop UI Components" there should be a link to the Style Sheets, which was e.g. http://doc.qt.nokia.com/4.5/stylesheet.html
Or, where is "The Coordinate System" formerly in "All Overviews and HOWTOs" a link to http://doc.qt.nokia.com/4.5/coordsys.html
Or where is "Rich Text Processing" ? formerly prominent in the Home Page under "Core Features" -> http://doc.qt.nokia.com/4.5/richtext.html

For me the new help is really a regression and makes my life harder to use Qt.