I wholeheartedly agree that SproutCore's documentation is poor. There have been plenty of reasons (and excuses) provided, but regardless, that still doesn't cut it. We're beginning to rectify the situation with Guides (http://guides.sproutcore.com) which was announced on Friday. There is already one written (http://guides.sproutcore.com/fixtures.html) and there are more in the pipeline, being written by both core team members and developers from the community. Given we're a startup, sometimes things need to take a backseat but Strobe is definitely committed to making developing web apps as easy as possible and documentation is high on the priority list.

Side note: I work for Strobe.