1. If a headless CMS is needed. 2. Need the cms UI to be clean. 3. There is a need for customization options in the UI and API as well. 4. Expertise in javascript and need cms with node js backend. 5. Want auth APIs pre-made. 6. Easy to customize the backend as well. 7. The user interface can be fully customizable.
Any small project which you want to have ready in a couple of hours would be probably a bad candidate for using Symfony. Even the most seasoned senior developer can easily spend hours or days creating a small MVP with Symfony. While Symfony's learning curve isn't necessarily bad and will depend a lot on the architectural knowledge of the developer itself, because of the modularity required by Symfony you will need to spend a significant amount of time coding. If you are looking for a quick project, perhaps this framework isn't the best solution. Robust applications can benefit from Symfony's architecture. I have participated in projects on different industries including lead generation, marketing and even some micro-services for other industries which use Symfony. Because of how thorough the framework has been architected, you will have a reliable solution.
Sonata Admin for Symfony is very versatile and we've used it for both the admin part of our website (even created a landing page constructor using it) and for the ERP system we've developed for inside use.
It is easy to learn if you know PHP and the community is quite large so you can easily find experts to help you with issues.
It's good for high-load projects. We have used it for the back-end of a custom affiliate marketing system that currently processes over 180 million requests per day.
It can be a little complex at the begining comapred to some other frameworks, but this gives very good structure and makes it bulletproof for scaling actually large applications. The framework is built in a way that you can start simple and bring incremental improvements to make sure your app responds to traffic, demand, and growing usage.
There is a lot of community support but because Symfony is so flexible and unopinionated, there are too many ways to do things and if you lock yourself into one way, most of the advice online will not work for you.
Symfony has become such a standard that many frameworks which previously may have been seen as competition, are actually adopting Symfony components to allow them to focus more on what makes their solution unique. Drupal 8 has replaced much of its low-level internal code with Symfony components. Laravel utilizes much from Symfony and builds on it. CakePHP was my preferred framework over Zend and CodeIgniter, but now I typically prefer Symfony or Laravel depending on the type of application and complexity of what I'm doing.
One negative thing to point out of Symfony is how painful it is to migrate legacy or relatively old projects from previous versions of Symfony into newer versions.
Symfony projects are usually reliable and provide the results you need.
Performance can be an issue sometime depending on the kind of project you are working on. Symfony can have some issues with cache.
