Yes, things have changed significantly for the better. However, there are still some pain points (more specifically debugging, especially on iOS as Apple keeps throwing curved balls)
Main difference is that ARC was being source of significant performance issues on mobile platforms. I have done extensive investigations at the time, and by doing slight modifications in FMX code I was able to significantly improve performance.
Used optimizations were covered in my blog posts:
https://dalijap.blogspot.com/2018/01/optimizing-arc-with-unsafe-references.html
https://dalijap.blogspot.com/2018/01/optimizing-arc-hard-way.html
https://dalijap.blogspot.com/2018/03/optimizing-arc-weakness-of-weak.html
Even though there is no ARC compiler, above articles are still valid when dealing with interfaces in Delphi.
Removing ARC compiler was not the only performance improvement. Next one was introduction of Skia library in Delphi 12, which gives better performance on mobile platforms. It is not perfect and depending on the project it is not necessarily working better on the desktop FMX applications, but it is easily configurable, so different rendering methods can be used depending on the platform.
Another pain point was using 3rd party frameworks on both Android and iOS, and this has also been significantly improved in the meantime.
Overall, plenty of bugs have been fixed in the meantime (of course, that does not mean there are no new bugs), but things are way better than they were at the early beginnings. Most importantly people are successfully using Delphi for writing Android and iOS applications. You can find one such example here:
Whether Delphi is the best option for some project that is another question and it can really depend on the project. The best option would be putting down all the tech your app needs to interact with and what are basic features you need to support. After you have tall that listed you can make a demo app to see whether you can easily incorporate all that you need across various tools and platforms. Only after doing that you will be able to tell which one will be the best for the project.
And at the end, the grass is not greener on the other side. For development Delphi is much more stable platform than some others. It does not have some fancy features language wise, but its UI frameworks are very stable. Over the years, both Google and Apple made significant shifts in their native frameworks that required extensive code refactoring (yes, you can still use the old ways, but it still requires a lot of work to keep up with changes). If you are looking for cross-platform tool, then situation is not too much different.