Personally I hated this extension and uninstalled it. The grammar checking function is extremely irritating (it doesn't seem to get the idea of casual English where you don't necessarily want to have loads of commas everywhere) and there doesn't seem to be a way of permanently disabling it. It also constantly offers me unwanted style guides for "improving" the style of my English (by upgrading to a paid version). This is probably fine if you are writing English as a second language, but it isn't suitable for native speakers wanting to catch awkward spellings or typos.