The Sony Xperia X was the first SONY device with Sailfish OS X

Sailfish X

It’s the new name of the Jolla’s OS, after the pivot towards a business based on the creation of software only. The UI and the apps are the same as in the Jolla Phone and Jolla C.
The entire interface has been adapted to the high-resolution display of the Xperia : the tests are more clear and legible ; the only graphic detail to change is the background texture (small black triangles), now less evident.
The Sailfish X license costs € 49 and includes Android support, Microsoft Exchange support and predictive text.
The installation method indicated by Jolla in this first phase seems to want to restrict the public to programmers : in fact it provides several steps and the use of the terminal.
Hardware side

The Xperia mounts the 64-bit Hexacore Snapdragon ™ 650 processor, along with 3GB of RAM, with Sailfish the battery lasts up to 3 days, compared to 2 of the Android version.
The storage space is 32GB, although currently sailfish seems to limit it to 16GB ; you can add micro SDHC up to 32GB, to make backups with the practical function under “settings / backup”.
The front camera is a good 23 MP and 24mm Wide Angle G Lens f2.0, the front one 13 MP. Still, the Sailfish photo application does a good job, even if the Sony camera software is of better quality.
The phone is left to grip well : it weighs 152g, while the dimensions are 143 x 69 x 7.7mm : thin enough, but solid thanks to the aluminum body.