Its fairly gentle as courses go, and all parts are explained well with all code written from scratch in front of you. It shows you how to do regular HTML first, before moving onto some of the advanced features.
So it starts with basic HTML together with inline styles, tables and input actions.
Then it moves onto CSS files and tailoring the result to look like what is required. It's quite fun to see the website evolving in front of you as you tweak padding, colors and so on.
Then it's on to HMTL5 new things. New tags, new form elements and so on. This is followed by graphics, video, geolocation, SVG graphics, mobile apps, caching and storage extensions.