I can't really comment much on current phones but as a dev I have come to own the Xperia Z3, Z5, Z5 Compact, XZ, XZ1 Compact, XZ1 Premium, XZ2 and XZ2 Compact for testing websites and Apps and I have here in Austria seen them in the wild from time to time due to Sony phones having been promoted quite a lot by local carrier - but that all was 5 or more years ago. These days I barley see them, and even if its always older Models from XZ times.
One of the things Sony through all these years always got right in my opinion is the Software. Sony's Software IS what reviewers say Oxygen OS is. Its 90% Stock and performance is always top notch and mega consistent for the given chipset. Even the Z5 despite having the controversial Snapdragon 810 puts out a solid and most importantly **consistent **performance to this day. Its not like with Galaxy S6 which is equally if not more powerful on paper but sometimes bogs down for no reason.
My biggest issue with these older Sony phones is their Screens. For some reason 6 out of my 8 Sony phones have some kind LCD related issues (Sony was also really late in using OLED) . My XZ1 compact has quite a few dead pixels and the other 5 have some brighter areas on the LCD which can look distracting. And yes some other brands have it too but maybe I got unlucky or something but Sony phones from my experience seem to by far the worst.
With their latest phones - I think they are in a great spot. They are a boutique Manufacturer with a clear audience in mind far away from the mainstream. I think unlike LG they recognized in time that they can't compete anymore in the mainstream and downsized the whole operation to what it is today instead of shutting the doors completely. This way people who really enjoy high-end notchless phones with a headphone jack and cameras that aim for authentic pictures still have very pricy option instead of none at all.
I am still a bit perplexed however on who buys the Xperia 10 phones for them to continue making them.