This app has fundamentally changed my practice in grading student essays. I love the Monkey Checker feature, because it allows me to automate low-leverage feedback items, such as formatting errors, so that I can focus on higher leverage, content-based feedback. I also love that I can build my own rubrics, and superimpose these rubrics and grades into Google Docs. This really allows me to keep all of my feedback in a single place, which in turn makes it easier for students to understand their feedback. Additionally, the added feature of building and sharing comment sets and rubrics with my colleagues helps with norming the use of this add-on across grade levels and subject areas. The updated user interface that mimics Google Classroom is an added plus.
Additionally, the JoeZoo technical support is top notch! When I encountered a bug within the app, their IT department responded to my issue within hours, and by the end of the work day had resolved my issue, allowing me to get back to work straight away. I cannot sing higher praises about this team.