If you want to know what's really bad with this phone, or cons if you will I can add the following:
1. On those later generations of Samsung phones there is a fuse that will get blown if one roots the phone or installs custom firmware on it (warranty void flag 0x1). This fuse will remain blown even if one restores the phone back to unrooted stock firmware. Towelroot can no longer circumvent this flag as it did with prior Samsung devices, yet, and who knows when it will be able to do it once again! The consequences of this blown fuse is that Samsung Knox won't work and so won't Samsung Pay. Also, this will make Samsung void warranty in countries where it is legal for Samsung to do so.This is a really BAD business practice! A smartphone today is no different than a computer, so imagine if Microsoft did the same thing with computer hardware. Microsoft locks down the hardware and denies the end-user admin privileges (i.e. root). The secure-boot "feature" of the UEFI was strongly moot and is now abandoned by private desktop and notebook users. Also, Apple tried the same 'warranty void' trick with the jailbreak thing and they lost while Samsung is so far roaming free, at least in the U.S..
2. The way the update to Lollipop is handled. Many users experience substantial issues with the update from KitKat, mostly with the apps that stop working after the update. There is no readily available option to seamlessly revert back to KitKat and downgrading to the prior firmware means that all data will be lost and all settings need to be reconfigured manually. Setting the updates to 'automatic' means that update from KitKat to Lollipop will happen automatically without asking the user first. This means that the phone will be unavailable for half an hour whether you like it or not. On Windows 7, automatic update may mean that the updates are checked automatically and upon availability the user will be notified and prompted before download and install. This is not the case with the Note 4. Lollipop is indeed an improvement over previous versions of Android, but just not on Samsung devices. Samsung has failed with TouchWiz and pretty much f*cked things up here. There is also no way to disable those update notifications should you opt to stay with 4.4.4.
3. Bug history and version history. Samsung is really bad at documenting and following up on things on the version history. I guess that there are several builds of say KitKat 4.4.4 featuring different updates to TouchWiz and other Samsung-specific parts of the operating system. But there is no way for the user to know what has changed with the different builds, he is completely left in the dark.