I spent an hour browsing this site. I am a faculty member who requires my anthropology students to complete written assignments. I grade the students' grasp of the course material and, although I do not grade their writing mechanics, I do note spelling, grammar, and punctuation errors. Since finding this high-quality site, I expect that I will direct students to it so that they can review particular rules about writing. In this way, students who desire to improve their writing skills can do so.
I encountered no technical problems whatsoever when using this site. Using the index is easier than using the drop-down menus that appear on the home page, although first-time users might like the drop-down menus to orient themselves to the resource.