I have found GB to be great for long form posts.

The ability to add css classes to blocks combined with custom css and saving blocks as reusable blocks means I can effectively create my own blocks.

My blog is based on Generatepress theme and this works very well with GB. I have been able to create a really nice variety of posts. For example a 4000 word long-read about the considerations that explores the process of designing a garden where I used GB to create a range of different magazine style sections. ( https://herbidacious.calamus.graphics/2019/09/16/creating-a-planting-plan-the-design-process/ )