In addition to the expected fixes and improvements, iOS 11.4.1 brings over a feature that's called USB Restricted Mode, whose goal is to prevent those iPhone hacking machines that law enforcement is using to bypass the screen lock from hacking iOS devices. As it typically takes more than a hour to get a warrant for police to be allowed to use a Grayshift box, this is quite a significant roadblock. As ElcomSoft writes, there are quite high chances of a device being seized within an hour since its last unlock.
With the lock in place, data cannot be transferred to or from the Lightning port; it can only be used for device charging.
What ElcomSoft note is that any USB accessory can be plugged into the iOS device within the hour safe window, and this prevents the timeout from ever being reset. Importantly, this only helps if the iPhone has still not entered USB Restricted Mode. That means if that someone plugs in a device like the GrayKey, favored by police forces in the United States, they won't be able to break the passcode protection and access the data on your phone. But for now at least, iPhones, with this update, are locked down.
Apple is rolling out iOS 11.4.1 for iPhones and iPads everywhere. Limitations in the MFI specification may make this easier to say than do however.
It's also worth noting that, even with the mode enabled, you won't need to go back to your settings menu every time you want to connect your favorite accessory to your device. As with most incremental updates, you can expect that other bugs have been squashed and that the overall stability of iOS has improved. With a 6-digit passcode, the new iOS default standard, it is practically unfeasible to attempt a brute-force attack at a rate of one attempt per ten minutes. The device can then be accessed once again through USB. The user maintains the only change to his device was the update to iOS 11.4.