I've got most of the AI writers promoted on Appsumo and they all seem to have their sweet spot. I wanted something that involved simple inputs and produced decent results longer than a single paragraph for web page content, articles and blogs. Katteb works for this purpose with some caveats.

Don't expect Katteb to be your final draft. This is not a comparative criticism; I've yet to find any AI writer that is capable of producing a final draft. Like with any AI writer, consider the output to be your rough draft. You'll have to proof and edit before you post on the web. It's not that the grammar is bad - grammar and spelling are good. Katteb however will produce a lot of redundant content in a long article. This is where I'm finding myself editing the most.

Overall, I plan to keep and use Katteb. As with most AI software, I think you can only expect it to get better with time. Currently it is a good start and will definitely save you time and money - which of course is the point, right?