Not for years: it’s 4 years old and Samsung no longer gives it security patches.
Before you pay: the seller signs out of their Google and Samsung accounts in front of you.
What to check before you pay
Five minutes that save you a headache:
Dial *#06#. The IMEI must match the one in Settings and on the box.
Google and Samsung accounts signed out, in front of you. Otherwise the phone stays locked when you reset it. Don’t buy a locked phone, not even at a discount.
Battery: Samsung Members › Diagnostics. If it heats up or drains fast, plan on replacing it.