If you come from the Note 4 as I did/do (still haven't gotten rid of the Note, and probably won't), and you LOVE the Note 4, you're probably going to find the G4 lacking.
It will remind you a lot of TouchWiz (the older, badly done versions, unfortunately), a lot of features will sound familiar from the Note, but Samsung trumps LG in the implementation on most of them.
The camera, however, you'll love. Having full manual controls is AWESOME. Sure, some features and settings are unintuitive and you don't have as many options as you have with Sammy's, but once you get the hang of it, it's a delight.
And of course there's the S-Pen. If you, like me, use it a lot, you're gonna miss it. DEARLY.