My Take
This is a great tool for quick navigation and reference of the Common Core State Standards. I currently coach and support teachers in the implementation of CCSS, so I use this app frequently in my work to highlight the vertical alignment and the correlation to the anchor standards.
How I Use It
This is less of a teaching tool and more of a teaching reference. It works great for a quick look through standards while planning! The biggest downside I have experienced is that the individual state additions to CCSS are not accessible here (e.g., for California-specific standards that have been added to CCSS, I have to go back to the CA Department of Education website).