EM UI, also known as Emotion UI, is Huawei's own skin layered over Android. The Honor 5X comes with EM UI 3.1 layered over Android Lollipop 5.1.1. There is an abundance of features packed into EM UI, most useful while others being more gimmicky than anything else.
Right off the bat, as soon as you unlock the device, you notice that there is no app drawer, there is no button that shows you a list of all your apps. Instead, they all show up on the homescreens just like on iOS. You can create folders and put away the icons you don't want to get in your way.
Though, organizing them might be easier than you think. You can organize your apps very similarly as you would with iOS, or you can create a folder by dragging one app icon onto another one. Once organized, the folder icons are grids rather than stock Android's stacks.
Naturally, one would worry about finding an app that's tucked away somewhere without a proper app drawer. You can intuitively flick down to bring up a search box. Typing a few letters will search through you apps, contacts, SMS, and even Twitter for any matching keywords.
If you dislike EM UI's launcher, you can always use an aftermarket one that suits your preference.
When setting up a fingerprint for security, the phone turns off all lock screen notifications by default so you would need to re-enable them.
Also, on the lock screen, is a quick toggle menu that can be accessed by swiping from the bottom edge that includes: music controls, shortcuts for voicemail, changing the wallpaper, settings, calculator, camera, and a toggle for the flashlight.
Setting up the fingerprint is easy and quick. Once set, a fingerprint can be assigned many functions other than just unlocking the device. You can assign a contact to a particular fingerprint which will unlock the phone and dial the contact upon scanning that finger. You can also use the fingerprint sensor to call the notification shade, the multitasking app switcher, or to answer a phone call.
There is also an Applock and a Vault baked into the UI, which will protect certain apps and gallery albums from opening until the correct fingerprint is provided.
Themes are also available on the stock launcher; you can customize themes by changing the lock screen style, unlock animation, wallpapers, icons and font. Unfortunately, there is no apparent way to download more themes and the Honor 5X only comes with three themes pre-installed.
Notifications can be customized for every individual app in EM UI. You can choose whether apps appear on the lock screen, banners over the status bar, and in the status bar itself.
There are also some pretty nifty features baked into EM UI like a glove mode, sunlight enhancement, and one-handed UI.
Among the accessibility options are: Talkback, Switch access, high contrast text, power button ends the call, raise to ear to answer, color inversion, color correction, hearing options, and touch & hold delay times.