We use Drupal to develop most of our clients' sites because the CMS features and the development framework give us the possibility to expend less time in the repetitive functionality, such as the user login or in the content management administration/creation.
We now have more time to focus on crucial features that our client needs, like custom mail notifications, statistics, or other features that can give our clients business value.
I think Drupal has to improve the UX for some administrative pages, such as the modules list page.
When I talk about improvements in user experience of the administration page, specifically in the modules list page, I mean that this page is annoying. It is annoying because the default interface gives us a list of all the modules in the site, uncategorized, and without the possibility to filter by text and to complete the activation of one specific module. Instead, we have to scroll down the whole page.
This is a problem because in live sites, the average number of installed modules is around 30 for mid-complex sites.
A module filter would resolve this problem. It would improve the Drupal modules interface, but an optimal solution would be to add UX improvements to the Drupal core.
I have used this product for around four years.
I have not really experienced any stability issues with the Drupal core. In some cases, we found some issues in the contributed modules. However, these bugs usually already have a patch available. If a patch doesn't exist, then we try to fix it and contribute back.
I did not encounter any scalability issues. The scalability/modularity is one of the principle features of this CMS.
The Drupal community gives excellent support to the Drupal core. Usually a reported bug does not last more than a week before it is attended to.
This is very relative. If you are using other contributed projects like the DrupalVM or Kalabox, the initial setup is less complex, because you don't have to configure all of the web stack (which is usually LAMP).
On the other hand, if you want to have your custom environment self-configured, you have to organize all the system requirements to run Drupal properly. This will include a web server (Apache, Nginx), a SQL database (MySQL, PostgreSQL), the PHP language, and helper tools like Drush.
As I said before, Drupal is free software and is covered by GNU General Public License, version 2 or later. You can find more information here:
https://www.drupal.org/about/l...
Every time prior to commencing a new project, we always evaluated the viability of the development of the project with Drupal. In one case, Drupal did not meet the requirements for the front-end of the site, but it met the backend requirements.
In that case, we developed two products, one front end developed in Angular JS and one Drupal as backend with custom web services to feed the Angular App.
I think the best advice is to be patient and persevering. Drupal is a very large tool and you will need to read a lot documentation and view some examples to start with it.