The Sony Xperia Z4 Tablet runs on Android 5.0, and that makes it one of the first Sony devices we encounter to boot Lollipop out of the box. Sony's customizations are on board as well, but they are ever so mild and the company's overlay is among the lightest around.
The lockscreen shows a single clock widget, with a choice of two digital faces and a single analog one, and there's also a camera and a dialer shortcut. The lockscreen notifications brought with Android 5.0 are here as well. Sony has enabled double tap to wake, but sending the tablet back to sleep requires pressing the power button.
The homescreen is the familiar shortcuts and widgets affair, but unlike the Z2 Tablet there is now a dock, and unlike the Z3 Tablet Compact it moves to the bottom of the screen when you switch from portrait to landscape orientation.
As usual, Sony offers Themes, which change the wallpaper and some of the system colors. There are several themes preloaded (plenty of wallpapers too) and you can get more online, both free and paid.
The notification shade is the stock Lollipop flavor, with quick settings toggles and a brightness slider, but no auto brightness switch readily available. The shade slides down in the middle of the screen and a two-finger swipe results in direct access to the toggles, while single-finger pull brings down the notifications.
You can rearrange, hide and add toggles, with Wi-Fi and Bluetooth always visible. Tapping the icon works as an on/off switch, while tapping the text below takes you to the relevant section in the settings menu.
The app drawer is laid out across multiple pages and you can sort the apps manually, alphabetically, or by the most used. The menu with those settings is accessible via a swipe from the left edge of the screen, which is the way Sony does things across its interface for a welcome consistency. You can also search and even uninstall apps from there.
The Xperia Z4 Tablet uses a standard-issue app switcher with the Lollipop rolodex look and a Close all button. There's a twist though and it comes from Sony's Small Apps. They pop up tiny widget-like applications on your homescreen, which you can move around and use without having to open the full-fledged app.
There's a default set of nine: Active Clip, Chrome Bookmarks, Browser, Calculator, Calendar, Gmail, Google Keep, Timer, and Touch Block.
You can download more Small Apps off the Play Store or use the option to turn your favorite widgets into Small Apps. Just hit the Plus key at the top of the list and choose a widget. You can launch only one instance of a Small App, but you can open multiple Small Apps simultaneously.
The small apps do offer added functionality, but the large 10.1-inch screen as well as the powerful hardware can handle more extensive multi-window multitasking features. With the tablet's business orientation, underlined by the available dock keyboard, those would have been more than welcome.