If you're paying by the hour/minute/whatever to surf the Internet, and you're wondering how cost-effective your time here will be, let me say a few words. The feedback I have received indicates to me that it takes most people anywhere from two to four hours to complete Introduction to HTML. That's including taking the quizzes, and it includes people who had absolutely no experience with HTML whatsoever when they started.
As to whether it will be time well spent, every piece of feedback I have received has been from users who felt they learned a lot, and most of them seemed to have enjoyed the experience. The tutorial has also been used as a resource for several college and secondary school classes, and as training material in many companies and branches of the government, and cited in several articles in the mainstream press. You can get more details on the Accolades page, if you like.
The tutorial is NOT currently available as a downloadable document. The reasons for this are given the Tutorial FAQ, so please read that before flaming me. This situation may change in the future, but even if it does, I couldn't say when.