Getting older models of phones isn't the issue it used to be as things aren't advancing as fast as they once were, a few years ago, particularly with Apple you needed to be on the latest or its immediate predecessor to get a good experience as hardware advances coupled with more demanding operating systems left you with the choice of not upgrading or having a slow problematic device if you took the plunge.
After the first few days with the note I've found it much larger and heavier then my S4,have a clear plastic case on the back at the moment and it does make it feels a bit on the large side, have ordered a bumper bar to try so this should improve. Might be as it's a new toy but I am Paranoid about dropping or damaging it due to the extra size and weight or scratching the screen in my pocket, battery life seems surprisingly slightly worse as is signal strength, not found a huge use yet for the pen as I had planned to use it to write shopping lists and other sad things but can't seem to naturally write without other bits of my hands touching the screen due to the size of the pen...
That said it's a pleasure to use. Great to type on, some apps like Opera work slightly different in a good way, no memory issues, tones of storage space..
Will assess it for a month to see if it's for me then think about staying with the note 3 or changing to the note 4,