Sony had a very rare insight when designing it. It's 10.1" with a gorgeous display and no burn-in after 4 years.
It is made of quality plastic, with rounded metal edges so it won't break when falling and a textured back. The thing is light, 395g. Nobody, even today can best this. Because it is light, thin (6mm) and with a textured back, you are never afraid you are gonna drop it. There is grip —remember, usually we don't use cases for tablets. Also due to the weight and how evenly distributed it is, you never get tired holding it. When I hand it to people, they are always surprised by the weight and how comfortable and nice it feels.
When most companies and reviewers optimized for aluminum, Sony had the mettle to go with what they thought better and they were right. Unfortunately, you can only value this, after you use the tablet.
They also made it waterproof. Submersible into water waterproof in 2015 which is very handy for a tablet, using it in a kitchen, etc.
It's a pity seeing them cutting more and more every year their efforts in the mobile division. Of course, they made mistakes, mistakes that I guess come from the company culture, but also the market is increasingly dominated by marketing practices. Let's not forget Samsung mocking openly apple users in their adverts.