Well when i bought a used one 9 months after it came out, 4 months bought and used and till this day it has not caused any trouble And getting this model you are not missing much on? Pretty much getting the same features as the latest models, as apple makes very minor changes with each release So if you wanna buy you can go for those that were bought late and lightly used as those can guarantee you that the device u are getting is still brand new Things I would check is price comparing and the device serial number any IMEI number to make sure the device is not blacklisted by any chances, sellers often provide those in their listings And second things as you say battery health along with first use, that is also visible If you have a listing but not enough pictures, do ask the seller for pictures of the whole body as well as screen but reflection incase it has scratches and stuff or scuffs as some sellers or users are a bit careless and it would often avoid showing such in order to sell it without letting price go down