As I've said before, a digital radio system is only as good as what you put into it. If you don't do your homework and test in all areas of your jurisdiction (at street level with portables) for proper operational service with the system, YES, there will eventually be trouble.
That said, same thing goes for every other type of radio system.
If you are using a conventional low band radio system and have 5 watt portables and are several miles from the base station, don't expect to be inside of a structure and TALK BACK to your base. You better hope someone AT THE SCENE can hear you OK because your dispatcher sure won't !
To fix that problem, many departments (police, fire and EMS) have added Mobile Radio Extenders (MRE's) to their vehicles. But again, you are LIMITED on the distance you can go AWAY FROM your vehicle and still get through.
Every technology has a drawback. When you use the equipment long enough, you learn what those drawbacks are and try to work within their limitations....