Here are some examples where the text could be improved, though really the whole page needs to be rewritten using the inverted pyramid.
1. "Api" should be "API".
2. "You're the skilled developer, so why would it be ok to settle for technical constraints as soon as there's manageable content involved?" is awkward. I actually don't know what you're pitching. What is manageable content? Why use a fill verb like "involved" instead of something concrete?
3. "prismic.io helps you make all your content adaptable to all possible designs." is passive. "prismic.io adapts your content to..." who knows.
4. "All possible designs" is clearly impossible.
Second, I still don't know what this does after reading the homepage.
Third, the title of this post was too vague. Maybe that was beyond your control. Did you submit it?
Fourth, almost all the graphics are not related to the application. Show don't tell!