OP... the Note 5 is the best phone I've ever used. With that said, the first three from early on, were terrible phones all covered under warranty. Batteries that did not last, hardware issues, The fourth phone... much better, has been running straight forward since last June. I've got an extended warranty as these phones with the non replaceable battery, can 'go' at any time or degrade to the point of just not worth the hassle any more.
Just because the Note 5 is a 64GB version, and I have the same, that means little if the phone is an older manufactured model that had early problems. You might luck out and get a great phone. Honestly, I'm VERY hesitant to buy any Samsung or any phone where the battery cannot be replaced, off of Swappa, Ebay and anywhere else. The whole non replaceable battery thing is a crap shoot.
Good luck!