The fact that it was a three-year-old high-end used and well-maintained car was a deciding factor in my decision to buy it.
I bought an A grade from a seller with a good reputation.
There was only one shallow round crack of less than 1 mm, very slightly near the centre of the screen, but it was almost unnoticeable if it was covered.
I thought it would be tough to get an A grade as the exterior paint was easy to peel off, but it was as clean as new, just by cleaning the grooves around the camera. I was very happy about this. However, I could not clean up to the grooves of the assist button because I did not have the right tools and gave up. I was able to clean it later with a special cotton swab.
The paint is smooth, so a cover is essential for this phone.
The battery is a 4500 model when it is new, but when I looked at it in the app, they all showed 4380 in the settings. It may have been a replacement.
However, the memory is a model that heats up to 40°C to 60°C in heavy online games that consume more than 2 GB of memory, so I think it would be good if it lasts two years.
I used it for two hours continuously, but the performance did not drop and it was stable.
In other cases, the temperature seemed to be below 40°C and I could use it stably.
When I actually used it in the application settings, the thing that bothered me the most was the colour of the screen. I set the white balance to pale white from the screen settings in the Android settings, and the colour tone became a little more acceptable. (But even at a colour temperature of around 9000, it's not enough for my liking.)
However, when using Xperia-specific apps such as Game Enhancer, the screen somehow becomes slightly yellowish, even if the white balance is adjusted to a more bluish colour. This is a matter of preference, and since it seems to be a specification that can't be helped, I decided not to use it.
I knew as information that it seems to come from the LCD of this model that it is greenish at low brightness, so I always set the brightness setting with a normal colour tone and use another app to apply a dark grey filter for nighttime, and I use it at night.
After five days of daily use, I decided to use it as it is because it seemed to function perfectly.
I would like to use this maintenance product again in a few years time.
~ Postscript.
I originally chose this model for music purposes. I enjoyed the improved speaker spread, but for some reason I got tired of listening to it. The sound quality seems to be about 10% different from the sound quality I prefer. I used the same songs, the same app and the same equaliser settings, but I couldn't get used to it for the first few hours. I tried many times to play with the equaliser and sound quality settings, wondering if the reverberation in my head was wobbling and the pitch was not stable, or if the high frequencies were simply too much, or if the volume was too loud. But it didn't go away for a week. I knew that I could just age it and tried several times, with breaks in between. So after a total of about 10 hours or more of ageing music with earphones and speakers, I suddenly got the sound quality I always like to listen to.
Now I just hope it doesn't break.