It condenses my words to be more accurate and understandable.

I am sure this app works great, but it is not what I want because it will not correct my spelling with out purchasing an upgrade.

does not work on firefox at all

Can't do spell check anymore, needs Premium. But getting a lot of features, which may Improve the writing, but looked behind a paywall.
Now it only shows me, that I have done something wrong, but doesn't show me that.
For a non English Native, it helped me a year prior, but not anymore.

Annoying. Gets in the way of me writing text.

I like it but it gets in my face too much. Most of the time, I don't care about my grammar because it's just some informal thing. I do use it when I want to be taken seriously, like when I complain to my congressperson about some bone-headed thing they did or didn't do.