I signed up for it as it seemed a great match for proofing my new web development framework Reken. The assignments are pre-created HTML pages, all completely styled. They just need interactivity added. This exactly the power of Reken. Bring HTML to live, as is, by adding some Reken HTML attributes to interact with it.
So far I have finished 14 assigments of the 24 and it is a blast, most of them were trivial to solve with Reken.