This is a review only for the first route of the game (Fate), not taking into consideration the second route (Unlimited Blade Works) or third route (Heaven's Feel).
First of all: this is a very long story. Unless you binge it for a lot of hours or skip through a lot of the plot, completing even one of the routes will probably take at least a week of reading. So far, the only other VN I've read of similar length was Majikoi, and I'd have to recommend it over this game because Majikoi didn't feel nearly as bloated dialogue wise, the protagonist is much more likeable and the h-scenes are much more satisfying.
I unknowingly played through Fate without the h-patch installed correctly, but I did complete it, so I installed looking for a fap but stayed around for what is ultimately a good, but flawed story. After actually installing the h-patch correctly, I went back and skipped through to see what I missed, and honestly...
I think the best experience is to entirely forget about h-scenes when looking to dive into this game. Leave it unpatched and focus on the story.
The artwork is good but the scenarios that result in sex feel weird and out of place when you consider the tone of the rest of the story and the personalities of the characters. I was left with the impression that the raunchiness detracts from the characters and their situations rather than complimenting them in any way. The version without h-scenes manages to be suggestive but keeps the story flowing much more smoothly.
That said, the plot is a good but is held back for me by two major factors:
1. There are too many bloated conversations where characters are painfully drawing out plot points and other details that could be expressed way more concisely. The breakfast scenes are particularly bad about this crap, but it felt like it was present in most scenes that aren't battles.
2. The protagonist is admirable in his own way but mostly a naive idiot. There are so many situations where he throws himself into harm's way unnecessarily or has some idea in his head that doesn't correspond with reality. Other characters point this out to him in various ways, so it's definitely an intentional character trait, but a lot of the time it's just frustrating to read. He also has the quintessential virgin personality where being within two feet of an attractive woman makes him sputter and freak out. That's pretty common for a VN protagonist but again, it gets frustrating to read after a while.
Regardless, it still deserves at least 4 stars because of the overall idea of the plot and the battle scenes. The characters, despite their flaws, are developed nicely and their personalities compliment (or clash) with one another in interesting ways. The action, sound & special effects are really nicely done and add a lot of immersion. The translation is virtually flawless. There are a lot of choices that lead to bad ends and most of them are really grotesque and bloody, which could be a negative for some, but I found it to be one of the more enjoyable aspects of the game because it made everything feel much more harrowing and dangerous.
TL;DR: A time sink of a VN that isn't worth it for the h-scenes but is worth it for the plot.