My experience is the Note 3's camera took forever to focus right, the Note 4 is a slight improvement, the note 4 is a little laggier for me than was my Note 3 (neither of them rooted).  The only reason I went to the Note 4 is that someone wanted my Note 3.  If not for them wanting my Note 3, in hindsight, I probably wouldn't have gone to the note 4.  I may go HTC the next upgrade I'm eligible for.  I have been a little disappointed with the Samsung line of phones, which is really bad because after 6 years of HTCs, I finally got fed up with them.  Funny how you don't know what you've got until it's gone.