First off, and perhaps most notably, Update 4.50 brings external HDD support. What this means is that if you’re looking for more storage space on the console, this update, will provide the option to store your extra content to an external HDD. All you have  USB 3.0 HDD into your PS4, and voilà, more space to hoard all of those Witcher 3 Roach screenshots.
The support will be compatible with HDDs up to 8TB in size. You can download and install applications directly to your extra storage, and the saved contents are easily manageable via the settings menu. Additionally, all applications saved in the external HDD will appear in the Content Launcher of the Home Screen, making it easy to keep track of what apps you launched recently.
Next up we have custom wallpapers. With Update 4.50 you will be able to set any in-game screenshot as the background image for your PS4’s home screen. According to Sony, drop-shadows on text, and the option to dim the Function Area, will help keep the system icons and texts on the home screen clearly visible even if the background image you selected is super bright (like a screenshot of Roach basking in an early sunrise).

PS4 Update 4.5
The update also comes packing additional improvements to the PS4 Quick Menu feature (the menu that appears after a long press of the PS button on DualShock 4). For example, now the Quick Menu will cover even less of your gameplay screen, and you’ll be able to access Party features via Online Friends, like creating new parties, inviting friends, and joining parties, without transitioning to the separate Party app. The goal of these improvements, according to Sony, is to keep you in the game, and not stuck in menus.
A simplified notification list has also been implemented. Before this update, the Notifications app had a variety of tabs on the left-hand side — i.e. Game Alerts, Downloads, Uploads, etc. All of these tabs have been condensed into a single simplified list, which in turn will make it easier to see all of your notifications all at-a-glance. Additionally, you will also be able to quickly access the Notification settings from the Options Menu to turn off or customize which pop-up notifications appear on your screen, therefore, you’re only being notified about the stuff you care about.
Lastly, courtesy of the new update you will be able to post directly into the Activity Feed, and be able to view 3D movies in stereoscopic 3D directly on the PS VR headset. The later needs no explaining, its 3D in VR. The aforementioned — the Activity Feed stuff — will work by letting users users click under What’s New, which via the new update will show new options to post things like text, screenshots, and gifs directly into your Activity Feed. You can also tag games or other users to make sure they don’t miss your post. It’s a great way to show off your sick Roach gifs.
Tying into this new feature, Live from PlayStation will show screenshots that users uploaded to PSN as a Public Activity, which means not only can your friends see your sick Roach gifs, but the whole wide world.
According to Sony, there are more features included in 4.50, however, this is all it decided to share today. Additional info, and launch time will be revealed “in the weeks to come.”