Watched it and I enjoyed it for what it is. More dialog with rider would have been nice. As is she is kinda just the muscle of the show where i remember her having more of a personality in the VN by this point.
The theater I saw it in was likely full of secondaries who didn't know their favorite franchise originated from a eroge so the finger licking scene and sex scene were quite hilarious with their open disgust/shock.
The whole Einzbern castle scene felt disjointed I dont remember it lacking any transitions in the VN but i haven't played it in like 10 years but that did make me kinda enjoy that scene less despite the animation being really good honestly.
I feel like a lot is lacking since we dont get the exposition from descriptions and bad ends like you do in the VN. Shirou feels less fleshed out for example and i think they had to add a few scenes just to kindof explain Sakura's obsession with Shirou where these things are done naturally while describing scenes in the VN.
overall worth my time and money even though i watched a cam rip of the thing a month or so before. I think the VN is still the superior experience though if you want to understand the characters more. Nasu just does that medium masterfully and i think isn't that great a writer outside the VN experience or at the best is a average writer outside VN.