Alright, so when we are in Tris' POV this is actually moving at a decent clip, then it switches and I still think I'm reading Tris, honestly I don't usually look at the chapter titles, and it throws me that she's thinking about herself in the third person and referring to herself as a man... Then I realise we've switched and my eye twitches a little. The concept is still strong, but the delivery has stagnated. 

So Tris and Four just so happen to have the exact same tonality for their inner monologues when the POV changes... Yep, awesome. Guys don't talk to themselves in that tone. 

Also, perspective hopping, always a blast, being the final book in the series this tells me one thing. Someone is gonna die by the end of it, how do I figure that? Because you don't do two thirds of a trilogy in First Person Present Tense from one POV and then just change it for a third instalment unless you plan to kill a motherfucker.