The screenshot below shows the My Home screen fully populated with all my installed accessories. The only one I elected not to have on the home screen, for the sake of layout, was the icon for the air quality sensor. You can add more icons to the home screen, but they appear below the two rows of five icons, and you have to scroll down to access them. The air quality icon doesn't change very often, and, like the other two sensors in the eve room accessory, they are read-only sensors. You can't control them, though you can use them to control automation. More on that later.
Apple Home "Home" screen showing favorites
In the upper left corner, tapping the location icon displays the name of the home (My Home), the connected Home Hubs and people to whom you've sent sharing invitations. You can also change the Home screen wallpaper or use the built-in camera on your iOS device to shoot a photo to use as your wallpaper.
The edit icon in near the upper right corner makes the icons on your screen "wiggle" so that you can rearrange them. Normally, a long press on an icon in iOS is used to enter the edit mode, but in the Home app, a long press on an icon gives you access to control the accessory.
The "+" icon opens a submenu that lets you add an accessory or scene. Surprisingly, the submenu does not include an option for adding new rooms. Figuring out how to add a room took a little searching through the UI. To add a room, navigate to a room page and a menu icon in the upper left corner of the screen lets you add new rooms. Alternatively, you can long tap an accessory icon, then tap the details icon at the bottom of the screen, and then select the Location menu. The Location menu shows the available rooms and also gives you the option to create a new room.
Status and Notification
The status of the accessories you chose to appear on the home screen appears below "My Home". If you tap on Details, the screen shows a detailed view of active devices included in the summary. The icons in the Status Details view are live, and from there you can tap to toggle them off. If you turn off an accessory there, it will disappear from this status details screen, and the text of the status will update accordingly. In the screenshot below, the Humidity sensor and temperature are grayed out, as they are read only. This screen also corresponds to the screenshot above and shows the same accessories are active as are shown in the Favorite Accessory portion of the screen.
Apple Home Status details
Scenes are merely groupings of accessories with specific settings that can execute as a single command. For example, for the Good Night scene, I've selected all of the accessories and have set each one to off. At the end of the evening, I can tap the Good Night scene icon, and everything shuts down. You also execute the scene via Siri by simply saying "Good Night" after activating Siri.
Similarly, I've created an "Office On" scene that turns on a light at 50%, turns on a fan, and turns on both outlets. Tapping the Office On icon turns the scene on. In addition to executing manually, can also be used as part of an Automation Script. The screenshot below shows the Scene Details for "Office On". Note the "Show in Favorites" switch is toggled on.
Apple Home - Scene details for Office On
Accessories that you have chosen as your favorites appear at the bottom of the Home screen. Upon initial configuration, the default setting has "Include in Favorites" toggled on, so virtually every accessory you add will appear on your Home screen until you explicitly configure it not to.
All of the icons work exactly the same way. For lights, dimmers, and sockets, a tap will toggle the device on/off. A long tap will bring up the control screen (below left). For this example, I chose the Philips Two accessory which is a dimmable light bulb. The control is a dimmer slider which you can adjust from 0-100%. For other accessories like Smart Plugs, the control is a toggle switch.
From the Apple Home screen image above, you can see that the accessory is on and is set to 5%, which corresponds to the dimmer slider setting. Tapping on the details icon at the bottom of the page opens the configuration for the accessory. Here, you can rename the accessory, change its location, included it in your favorites on the home screen and include it in the Status/Notifications. As noted above, the location menu is where you can create a new room and add the accessory to it. Not shown because it scrolled off the screen is additional information about the manufacturer, the serial number, and the option to group this accessory with other accessories that could be treated as a single group.
Apple Home - accessory control (l) and accessory config (r)
Finally, across the bottom of the Home screen, you'll find icons for Home (currently selected in above screenshots) Rooms, and Automation. I'll discuss Rooms and Automation separately.
The Rooms view shows detailed information about a selected room. All accessories assigned to a room appear at the bottom of the screen with each icon showing its current status. Above the listing of accessories is a listing of scenes. A scene will appear on a room's page if any of the accessories in that room are selected for that scene. In the screenshot below, at least one accessory is in each of the three scenes. As on the Home page, a long tap will open the scene for inspection/editing. At the top left of the screen, there's a menu icon which all of the available rooms. This menu also has an option for creating new rooms or changing a room's wallpaper. To navigate between rooms, just swipe left or right.