The system will boot normally and won’t look visually different than it did before. However, drivers installation won’t be blocked entirely. This time, the system will be as hospitable as Windows 7 for new unsigned drivers.
This mode will last for only as long as the system is up and we’d recommend you restart as soon as possible in order to make your process worthwhile.
If you like, you could find out other articles about Windows 8.1 and the changes that it has been through. Feedback is appreciated.