The first problems or disadvantages is the heating issues, not under gaming but while charging the battery with the supplied Turbo charger. The heating is experienced exactly on the battery. However there is a way to get rid of it by switching the device off while charging.
Second Moto G4 Plus problems or cons is the radiation levels which is measured by SAR values and its very high. Its of 1.086 W/Kg at the head and 1.48 W/Kg at the body.
The navigational buttons are placed on the screen itself, means there is no dedicated navigational touch buttons. There is no any real problem but it uses the real-estate of the gorgeous full HD display.
The 16 megapixel camera cannot record videos in 4K resolution which is a cons or disadvantages.
Next Moto G4 Plus issues or cons is that it does not support VoLTE which is important for making voice calls over LTE networks.