Bubble

1) Design flexibility: the freedom of working with a blank space, which requires probably more time investment and craft building in both design and workflows, but allows a lot of flexibility and almost limitless possibilities.
2) Data relationship: the logic of the database, where instead of relations between tables, it works with fields as objects to access records in other tables. In the beginning, was hard to get used but once I got it, it is just a superpowerful logic.
3) Privacy/access settings: the privacy rules, workflows and hiding properties which combined allows making parts of the app and database public or private for specific users, and therefore for public webs, internal apps, customers apps.

It’s major achilles heel for me is the expression system, both for allowing more complex logic and better expression editor (right now is a mess editing an existing dynamic expression). Implement a good condicional logic (case, if) along with internal expression variables (let) would allow making almost anything.
This is really a huge thing, it is difficult to describe how this impacts or may impact an app, the complex logic and expressions (complex conditional expressions, better editing, variables) is the 50% of a complex real application. Improving this, would make Bubble a fantasy, a total killer solution.

The best thing about Bubble is that you can make changes quickly and that you learn it extremely fast.

- The lack of dynamic widths in the elements, it follows that when you change the text, you have to adjust all the affected elements.
- The speed for complex applications is unfortunately much too slow
- Some rudimentary elements are missing and can only be supplemented with plugins -> But these are usually also not always well implemented

It's a mature platform and has great features for web apps. It's easy to create complex apps. The UI builder has total freedom. The DB is easy as in Excel.

All these freedom come with relevant limits and poor UI performance compared to actual code. There's no way to create a native app. You can create a web page that looks like an app, but the performance is poor. Also, there's no access to the code, so what you build is locked-in in their platform.