I upgraded from the S5 to the Note 4 on Verizon Wireless last week.
I know this is stupid... but I hate the alarm app.
When you set an alarm, it sounds off for about 40 seconds, then goes into an automatic snooze. It will sound off again, depending on if you set it to 3 minutes, 5 minutes, 10 minutes, etc, but, what genius in what universe decided an alarm clock needs to function this way? I had to install some other app from the play store. The Galaxy S5 had the same problem.
I havent noticed any lag problems yet. I am having trouble with getting my right thumb to reach across to the left side when holding it with one hand, but, hey, its a big phone, and I knew that going in, after trying it in the store about 15 times. I have a few apps set so they are smaller. I think I have them set for one-handed function.
I also dont love the new car mode app. The navigation button now takes you to a 2 screen option. I usually just want to see a map, I dont usually want to put in a destination. MAP is now on the 2nd screen, and now its more taps. Not too big of a deal, just more irritating because it was simpler and easier on my S5.
I also wish it had the cover for the USB port.