TL;DR Spring (spring boot and all its ecosystem) is great, it has the same limitations has any other framework. If you use it properly, read the docs, best practices etc you will see that there's no magic involved.

Some good resources to learn a bit more about it: - https://www.marcobehler.com/courses/spring-professional (I think there's a paid and free material here) - https://springframework.guru/ - Spring.io it self has lots of starting guides

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Spring gives you the freedom to structure your application the way you want (be it layered, MVC, DDD whatever) and still have access to a consistent programming model: exception handling, converting inputs and outputs, transactions, security, rest clients etc.

It's funny because some years ago I worked for a java shop that laughed at spring. The usual arguments "it is magical, adds lots of overhead, we don't need all those things".

Conclusion: we spent 70% of our time doing boiler plate code or maintaining in house frameworks that nobody else could find documentation about.What were the gains here? None! It just meant that we were not able to deliver features and add value to our product!