I'm more than satisfied with my purchase. I knew about its length beforehand (I think most of us that access game sites know how short is was) and was actually surprised how much time I got out of it. I have spent 15-20 hours on it and I'm at 89% completion with only 1 trophy left. The game is absolutely beautiful on PS4, however you could tell it is essentially a 1080p/60fps version off the PS3 (which is very nice as well). This game plays the best in any Metal Gear title to date IMO, and it did what it was meant for, introduce the sandbox style elements and controls. TPP is going to be much better than GZ in terms of scope and everything GZ did, it will expanded on, that excites me a lot!
The one thing that surprised me the most was the A.I. I don't know about you guys, but playing on hard (especially the day time missions) and turning off reflex and marking, this game is HARD. VERY HARD, its tough to even go "rambo" on them because of limited ammo and amount of damage you can take. And the enemies have like Eagle vision, long gone are the dumb A.I. from previous titles.
One thing that I found most disappointing was that 3/4 of the game's cutscenes were shown in trailers :/
I told my buddies that aren't too into MGS to just borrow my copy and to buy The Phantom Pain, pretty much this was made for the MGS fans (although not all fans were satisfied).