There are side-effects but usually only during the first few weeks and are relatively minor compared to dealing with HIV. If you are barebacking at all then you should be using it.
The problem with PrEP is that people will start barebacking once they're on it as the main scare is HIV. Problem with that is HIV isn't the only STD and PrEP only protects against HIV.
So all the other diseases spike in areas where PrEP is widely used.