This is a lovely tool, the writing has come out really well . I'd recommend in the you explore the tone that suits your style.
On an average, it's 5.7 -6.0 characters per word , tested multiple times. If you are looking for long form with multiple tones & variations , expect to hit 5 articles in a month on this deal.
Once your strategy is streamlined, maybe 6-7 maximum.
Tool uses the DaVinci engine which is highly rated and grammar and plagiarism checks are fine so far.
With all of the above and a simple and neat UI & UX I'd recommend the yearly membership.
I have both Contenbot and Nichess and suggest this would complement the latter better from a workflow perspective. (still early days)