I put a 'BestSkinsEver' skin on the front/back my Plus on day 1, but also bought a few cases, and as much as I want to keep a case on it for protection, the phone feels much better in my hands without a case (just with the BSE). I can grip the phone much better with the skin on versus a Spigen Neo Hybrid. I will say the Apple silicone case has awesome grip but the case picks up every speck of dust from my pockets, and because of that I have to take it back.
If you are going to rock the plus without a case, at least make sure you have Apple Care.