Plenty of nefarious applications for this. The range alone blows away existing RFID designs, which will make it the preferred "chipping" technology for surveillance states everywhere.
That said, the potential for abuse is limited by what society will tolerate. We tolerate tracking and alcohol monitoring bracelets for people who drive drunk. If we tolerate tracking implants for sex offenders on parole or something I'm sure it'll filter down routine probation sentences eventually.
You can leave your smartphone at home.