First impression, greta works like magic.
I have tried to create two apps.

What I like the most:
1. can create full web apps, in single command. (we need to write a proper instruction, as detail as possible).
2. It integrate with GitHub, so you can clone it to your laptop, if you need to manually edit the content. And greta can pull the updated code back to the platform

There is still improment needed.
1. May be if there is a form or guided prompt, to create the app for the first time. I imagine something like: what is the purpose of the app, what menu should be available, do you need registration and login, do you need admin panel, etc. check box. We can just fill the form, hit the button, Greta do the rest.
2. If it can also convert the web app to mobile apps.