I had a flip phone for years and swore I would never get a smart phone. Until I got promoted to Sgt and had a team of 10 guys texting me frequently. I couldn't keep up on a flip phone with the press the #3 key three times to get a "C" etc type typing. I switched to a smart phone and it helped tremendously in doing the job and I liked it for personal use. I used it then as an all in one camera, faster/easier texting device, GPS navigation replacement, calendar and phone. I added a pill look up app, Hero 911, Radar now, and a couple other apps. I never used it for social media (almost no one at my agency had a FB account after a negative incident) and rarely for email or internet search.
Obviously they can be great tools if used wisely and significant impediments and safety risks if not. Finding the balance is more personal than policy but both are important. The use of the devices for scanning VIN, Electronic citation issuance,licenses and the like will likely mean more use for the job.
It is important to separate job use from personal as if you take a photo to be used for evidence purposes the personal phone can wind up in the hands of prosecutors and defense lawyers. Our legal council addressed this at a legal update and personal use went way down as it should.