First off, I hate giving grades. A through F are meaningless to me. Yet I'll give it.
5 tacos = the platform is easy to use, easy to understand, and has enough features, and a lengthy enough prompt space to get "mostly what you want."
4 tacos = because it does not allow me enough space to enter enough of my own previous content, so that it learns to write like me, use my lexicon, my voice, my style, and build upon what I already know and want to convey.
3 tacos = because it does require me to go through the manuscript carefully, and edit, change, improve, shift the tone, etc. Which is a great deal easier than writing and editing from scratch, and on a Word, Pages, or Scrivener doc. (I LOVE Scrivener by the way.)
5+ tacos = because I have invested in their journey, and so far, this is the best I have seen. Certainly better than the AI platforms, which do OK, but chunk by chunk, by chunk.

I am glad that I invested in it. I use it 2x a week. And, foresee using it monthly when I am the mode.