The game is amazing in all the ways that count, battle system, story, character interactions, side quests, graphics, nostalgia, voice acting, cinematic events, plot progression, etc.
The game is frustrating due to being in installments, the story being similar to but also very different from the original, the focus of Dissida, FFXIII, and timeline universe alterations in the finished product. The focus is less on discovering who Cloud is through the death of Zack, Biggs, Jessie and Wedge, opting more for the interactive tension between him and Sephiroth Advent Children style.
What it does right: many original elements such as materia with new elements like weapon upgrading. Old challenges like endless Shinra battles, cross dressing event, workout challenges, acquiring gil and items. Music and cinematic events. Battle system is very polished and each character feels unique. Cloud looks less like advent children and more like his original self, with each coliseum battle feeling epic as he mounts his sword to his back in the iconic way he always has. Tifa is deeper explored in earlier scenes then she did in the original, looking at her motivations. Barret sings the iconic victory music upon victory in a battle. Quests do not feel repetitive, and are essential to maxing your playthrough though easily skippable if you are impatient. Hard and normal mode for replayability with continued progress and levels progressing to 50. Voice acting.
What it does wrong: changes many story points, some for good others for worse. Items are useful early and pointless later. Sephiroth is really freaking cool, and this may seem trivial, but he has cat eyes? In normal you focus on maxing everything but in hard mode its all about finding a specific pattern and materia combination to every enemy (good and bad). Alternate universe or parallel universes (cool in a scientific way but scary as a long time ff lover seeking authenticity to the original.
While I'd say I would rate a 5 from love alone, and a 2 for 100% graphics overhaul alone the story being the same (because it is very different). I give the grade of 5 as in play it for what it is, and 2 for expecting it to be ff7. 3 is an average score.