Its tough to rate FS/N fairly for a few reasons to me. First and foremost is the juggernaut of a franchise it spawned. Fate is one of the most successful and massive franchises of its genre and it can be hard to remember this started as an ambitious story and not the beginning of a decade-long franchise.
This game has been a 4 year journey, I've played it on and off for longer than any other story-based game, so as a whole, it feels a bit hazy. Despite that, I really did enjoy it
The first route, Stay/Night is a solid start that heavily emphasizes establishing ideas and characters and playing by the rules. Its simple, but the arc between Shirou and Saber hits very hard. Even if Shirou acts like a sexist prick thanks to his martyr complex.
The second route, Unlimited Blade Works, is far and away my favorite. With Archer and Shirous's dynamic and story are so well done and poignant. Fantastic stuff there. Berserker is simply built better
The final route (and the freshest in my mind) Heveans Feel is probably my least favorite. Sakuras story doesn't feel as tasteful as it probably should have and her and Shirou can't keep it in their pants its crazy. But still fulfills a great conclusion.
Overall FS/N is keen to leave no story beat unexplored. Any and every rule it establishes is broken completely and cleanly, the story always curveballs at moments that leave the characters heading in a direction completely new.
I think 4.5/5 may be a bit nice to it for its amount of 2000s anime bullshit, and being an eroge (TBH when highschool me downloaded this from 4chan thinking the sex scenes would be a funny joke, he was not planning on college me groaning to death when Sakura and Shirou can't be mature for a full day.) They really suck not a fan! The rerelease removes em I think should have played that.
With that rant out of the way, yeah its good.