The previous seems to be missing a few screws. They argued that "The Hill of Swords" had:
1. No character development.
-I'm confused. Where did this come from? Shirou specifically notes (multiple times) how Louise has developed because of his influence, and Louise pushed Shirou to realize that he has changed, during the third arc. And in the author's notes, GB says that "The Hill of Swords" is supposed to be about Person vs. Self, not Person vs. Person.
2. Changed all characters.
-Most Familiar of Zero characters start out virtually identical to canon, but they start to change once they interact with Shirou. Saito's the only 'character you knew and loved' who's missing.
3. Too much detail.
-If a crossover involving Nasuverse isn't full of detail, then it's either crack or poorly written ("Miracle" is the only exception I've seen to this rule). A writer shouldn't rely on a reader's imagination when they have a specific idea in mind. I can't count the number of times I've given a general description in D&D, only to have the players reach completely different conclusions about whatever I described.
4. a poorly written ending.
-This is a legitimate problem with the story. Ending after a massive timeskip is not a good idea.
"The Hill of Swords" tends to divide its readers into haters and fanatics. If you're just looking for "Familiar of Zero" characters engaging in familiar harem antics, this fanfiction probably isn't for you. Otherwise, it's a great read.