A revised review detailing more on the flaws of the story. Note that this is written when the story is still at the 18th Chapter and 350k words in, which is stated to have just finished the beginning of the first part of three.
The story. Good premise, but poor plot. 350k+ words (equivalent to 5 LN Volumes) in and there's still no true conflict where "Shirou" has to go through the hard way and change. There are fight scenes here and there, but it's just that, no true conflict, much less a theme and a value. The plot is just your usual "Be awesome and try to go home" story. The pacing was worse than even gabriel blessing. If it wasn't for one interlude, the story's direction would've still been unclear. The inner working of the story is very poor.
The characters. For the Fate side, they are all mostly very much derailed. It didn't matter what the reason was, the fact remains that they have been changed without a proper process. The characters are changed to fit the story, instead of the reverse, which is a sign of bad storytelling skill. On the Campione! side, no developments at all, the only times they were used is to show reaction towards the Fate cast, often remarking on how 'dangerous' they are. There are way too many OCs, most of them aren't even interesting. Some were interesting but as time goes on, the traits that made them interesting in the first place was gone. This is my biggest disappointment for the story as they stole the spotlight from the Campione! cast despite them being much more interesting characters.
The Canon. Thrown out of the window. Most of the mistakes in the Nasuverse mechanics came from the Author's Note and subsequent attempts to fix it there. Instead of using elements that was already present in the Campione canon, it just made original storyline that came out of nowhere, which also relies on original characters.
The writing techniques. Fine, but aren't very stellar either. Too ineffective, too many repetitions, too many unnecessary details. The prose aren't that great, and it is way too long, following the usual beginner mistake of length=quality. Content:Length ratio is very much low.
Overall, it is very much flawed, if you turn on your brain and try to see them, then you will see them. If you turn them off then you will see a very 'awesome' fanfiction, albeit one with a shallow story.