And things have changed again since Sony launched this tablet in 2015. There's now competition from Google with the Pixel C as well as two new iPad Pro devices to compete with. The Nexus range has even dropped out of the tablet game altogether.
Sony had the chance to smash and grab with a fantastic Android tablet and it made a good product - it just did not seem to sell very well.
And now there are even rumors of a Sony Xperia Z6 Tablet in the works as well - it'll be skipping the Z5 to keep up with the number of the flagship phone range - but no details are firm at this time. The main question is, is the Xperia Z4 Tablet still worth buying?
Design and display :
Sony's design is as polarising as you can get – you really do either love it or hate it.
If you can see what the brand is trying to do, then the first thing you notice when picking up the Xperia Z4 Tablet is the weight. It's lighter than ever before at 392g, and the difference is noticeable.
The back of the Xperia Z4 Tablet isn't as cheap-feeling, or looking, as on previous iterations. This time around it's a high-end polycarbonate material that, while not feeling as nice as the iPad's brushed metal, looks great and feels easy and comfortable to grip.
Sony has managed to make the slate even thinner this time around, without giving it a flimsy feel. It's only 6.1mm thick, the same as the iPad Air 2, but you get the feeling it would blow away a little more easily than Apple's slate would.
At one point I was taking some photos of the sky with the Xperia Z4 Tablet (for reviewing purposes –I'm not into clouds or anything), and I did have to tighten my grip at one stage due to a slight gust – if you weren't paying attention this tablet could easily be blown from your hands.
Sony's infamous flaps are once again in play, there to keep the tablet water- and dust-resistant to a high degree of IP65 and IP68, but they don't protrude as much as on previous models, and are a lot less obtrusive at first glance.
The Z4 tablet is sturdier too, despite being thinner. When reviewing the Sony Xperia Z2 Tablet I managed to break off one of the flaps by mistake – it just snapped off in my fingers when I was trying to open it to charge the tablet.
This time around Sony has taken the criticism of the flap system on board, and while not replacing them entirely, it has refined them to make them a little sturdier, and much easier to pop in and out without the risk of them coming off.
The waterproofing is a big bonus, and makes the tablet a lot more useable around the house – take it into the bath to read a book or watch a video and you won't have to worry about it slipping from your grasp.
I find the feature particularly welcome when I'm cooking – it doesn't matter if you manage to slather your slate in flour and grease while using your grimy finger on a recipe app, as you can just wipe it clean.
It's worth bearing in mind that Sony has recently said it doesn't recommend using its products under water even though they are waterproof. It basically means don't leave your tablet in water for days on end or get it soaking wet a couple of times a day.
Although the waterproofing arguably makes the Z4 one of the most robust tablets on the market, the rest of the design does give you the feeling that it would snap on the slightest drop.
The power button is on the left-hand side, with the volume rocker just underneath. Both are difficult to reach, but it's not clear where they could be better located on a 10-inch slate – you'll just have to deal with the fact that you'll be using two hands when changing the volume or turning the screen on and off.
A big design change is the lack of a dock connector at the bottom, which enables the tablet to be made that little bit thinner.
Display:
The display is a 10.1-inch stunning 2K job with a pixel resolution of 2560 x 1600. It looks great, delivering really sharp images, and is a real step up compared to the 1200 x 1920 setup we saw on the Xperia Z2 Tablet.
Watching video is a real treat here – you're getting 299 pixels per inch sharpness, better than the 264ppi on the iPad Air 2, in addition to the screen itself being significantly bigger than Apple's alternative.
As with previous models, Sony has surrounded the tablet with pretty hefty bezels. These have been whittled down a little further than on the Xperia Z2 Tablet, but they're still quite cumbersome.
I like them though – I've got some pretty thick thumbs to fit in those bezels and it means I'm not tapping the tablet when I'm focusing on a different area, as I sometimes find myself doing with a caseless iPad.
They're not to everyone's taste, though, and Sony could do with shaving them down a little more and making the slate a little smaller overall.
The display reproduces colours beautifully. Whether you're using apps,watching video or just browsing the web the image quality is very impressive.
The screen brightness leaves a little to be desired though; while using the tablet outside I sometimes struggled to see the picture clearly, and got a lot of glare off the front.
I didn't have any issues while using it in our brightly lit office, but you're likely to need to set the brightness to maximum when you're out and about.