I upgraded from a Samsung Prevail (which I loved!) to this. I am not impressed at all with the bluetooth on this phone. My prevail synced easily to my car and I never had any issues running Pandora or anything with it. The J3 has a hard time syncing to my car and continuously can't find the network and doesn't let you change channels on Pandora at all.
Also, the front facing camera always takes blurry pictures up close. If you're trying to scan receipts for Ibotta or the Walmart Savings Catcher apps well forget it because this phone can't take clear enough close ups for that. I still use my Prevail for scanning receipts which kind of defeats the purpose.
As for the Fitbit app, it works well enough, but takes forever to sync sometimes.
Not impressed at all with this phone for the money. Wish I could return it but it's been too long.