The 5th generation of wireless networks addresses the evolution beyond mobile internet to massive IoT (Internet of Things) from 2019/2020.
The main evolution compared with today’s 4G and 4.5G (aka LTE advanced, LTE-A, LTE+ or 4G+) is that, beyond data speed improvements, new IoT and critical communication use cases will require a new level of improved performance.
For example, low latency provides real-time interactivity for services using the cloud: this is key to the success of self-driving cars, for example.
5G vs 4G also means at least x100 devices connected. 5G must be able to support 1 million devices for 0.386 square miles or 1 km2.
Also, low power consumption is what will allow connected objects to operate for months or years without the need for human assistance.

Unlike current IoT services that make performance trade-offs to get the best from current wireless technologies (3G, 4G, Wi-Fi, Bluetooth, Zigbee, etc.), 5G networks will be designed to bring the level of performance needed for massive IoT. 

It will enable a perceived entirely ubiquitous connected world.

In short, that’s what makes it transformational.