I thought Grammarly would make me lazy. On the contrary. After about one month of use I found that I no longer make mistakes worthy of Grammarly corrections! I do appreciate the automatic typo correction that is not your normal auto-correct.
I was great before and now I am an expert.
Worth EVERY penny.

Latest reiteration continuously adds it's cookie onto your PC even when not in use, so it's tracking every move of yours. This is a huge privacy issue. Uninstalled.

Terrible performance hog - it slows Firefox to crawl, makes it practically unusable for browsing the web.

It was quite a good plugin until they start to label people based on their nationality, race, and color.