Software: Slightly Tweaked Android 4.3
Out of the box the Xperia Z1 Compact is running Android 4.3 'Jelly Bean' with Sony's custom skin, so it was already one Android iteration out of date from the moment I started using it. Sony says the device will receive an upgrade to Android 4.4 'KitKat' sometime in the future, but when exactly remains unknown. Ideally a brand new phone should come out of the box with the latest version of the operating system, but we don't often see this happening and it's an issue with most Android OEMs at the moment.
I'm a big fan of the vanilla Android design, so it's always disappointing to see a manufacturer ditch the stylish Google-made visuals in favor of their own concoction. It's even more disappointing when the skin applied across the operating system and its applications doesn't add any new features, a phenomenon I like to call 'skinning for the sake of skinning'.
While the Xperia Z1 Compact's skin doesn't add many features, and is essentially skinning for the sake of skinning, I can forgive it somewhat for not being a 'heavy' skin. Unlike Samsung's TouchWiz, HTC's Sense and LG's custom UI, Sony has gone for relatively modest modifications with an overall style similar to stock Android's.
Most aspects of Sony's skin are unspectacular and add little to the Android experience. The lockscreen can take you directly to the camera app with a swipe, and there's an array of quick settings at the top of the notification pane that can be interchanged. The homescreens themselves are as standard as they come, with first-party widgets that you've seen and used before in one form or another.
A number of the standard applications on the Xperia Z1 Compact are stock Android derivatives that are visually pleasing, but add few (if any) features. I like being able to see my agenda along with the monthly calendar in the Calendar app, the People and Messaging apps are simple and functional, and the Album app is feature rich yet fluid.
I'll take the time once again to highlight Sony's Walkman app that's included as the first-party music app on the handset. It integrates well with Sony's Music Unlimited service (if you subscribe to it), but if you'd rather use local media, the interface is nice and the app can pull a ton of metadata to improve your library. Walkman is also one of several apps that can link up with your media servers, not just to pull in content, but to share it with your local network.
Another great app is Smart Connect, which performs actions automatically when certain conditions are met. For example, when the charger is connected during the evening, the Z1 Compact can be set to automatically switch to silent mode. Or when headphones are connected, music can automatically start playing. Unfortunately the app is quite limited in what criteria and actions it supports, but it works reliably nevertheless.
If you aren't a fan of Sony's applications on the device, you can always download the range of stock Android applications that are available in the Play Store courtesy of Google. While I have no problem with people downloading stock apps through the Store, I'm not a fan of the inclusion of some of them out of the box.
Having the Walkman app and Google Play Music, Album and Photos, Messages and Hangouts, and so forth, creates a bad user experience. Performing many actions on the Z1 Compact results in an app selection dialog, which is jarring and potentially confusing for some users. Should I choose Album or Photos to view this image? The Z1 Compact gives you no clues which app to launch.
And it's a tricky problem to solve, because Google bundles some of their apps with their almost-mandatory Mobile Services, creating clashes with Sony's replacements. Sony could ditch their apps entirely, like they have done in bundling just Chrome on the Compact, but that kills any chance of expanding the software's features.
Some added features take the form of additional applications. TrackID and TrackID TV use sound data to inform you of what song you're listening to or TV show you're watching, Socialife aggregates news and social media sources, and Sketch is a basic drawing application. PlayStation Mobile gives you access to some exclusive Sony-made games, adding to what is available through the Play Store.
There are a number of other apps that have been slapped onto the device, including Box, McAfee Security, Autodesk's Pixlr Express, OfficeSuite, QR code reader NeoReader, and an app that wouldn't even load for me called Xperia Privilege. Most of these can be uninstalled if you'd rather not have your device filled with bloat.
In terms of additional features you can find in the smartphone's settings, there's not that much to be found. The Xperia Connectivity section allows you to control the media sharing features of the Xperia Z1 Compact, and gives options for screen mirroring and connecting DualShock 3 controllers for gaming. Under most other headings you won't find anything exciting, as Sony has largely stuck to what's included as standard with Android 4.3.