Opening scene was pretty great; Sakura rolling over Rin and Shirou, Saber doing the same to Rider before cutting to the opening crawl with Kirei speaking. I had just recently rewatched F/Z so it was a bit of a surprise and a delight to see Kirei open the garage and have a motorcycle and what might have been a car similar to the one Irisveil and Saber drove around in during Zero. Probably not, but that's where my mind went so I feel that was the intended effect.
One of the few theater laughs came soon after they headed to the Castle to retrieve Illya, when Shirou came flying in through a 3rd-floor window because Kirei couldn't handle him inching his way along the wall. Pretty damn great! Nice to see Sella and Liz again. Another slight chuckle at Shirou jumping back down to the ground; should have broken his legs, but tanked the shock like a boss.
Splitting up for their individual battles, I'll start with Kirei. The battle against Assassin was fairly short but it got the important parts down. I appreciated the addition of Kirei's inner monologue about his wife and child - or at least I think that was added, been a while since I actually read HF so I don't recall if that was there before or not - and him pining Assassin to the wall while he went to the roof to put down Zouken with that epic fucking prayer. Good shit.
Back to Shirou and Illya, seeing them bond a bit before Shirou resolves to go face Berserker was touching. The 'keep up with me' section felt a bit odd at the start but I quickly settled into it. This was the only time that an EMIYA theme played to my knowledge and it worked well, though the visual of Shirou diving off a cliff after passing Archer... I don't really know what that was meant to symbolize. Nine Lives was great for the most part, but the triple-spin before the final slash/stab was unnecessary imo; probably a director's choice to try and give it more impact, but w/e. Seeing Herc cry over his kids in a small flashback before he reverted to be uncorrupted with one line of dialogue was a good surprise as well.
The prep for getting the Jeweled Sword definitely did feel a bit rushed, quick glance over it before Illya takes Shirou into the flashback to get a visual on the Sword. Admittedly at the start of the flashback is when I went for my piss break so I can't really say much, got right back at the end as Zelretch pointed the Sword, and the scene cut.
The Rider/Shirou scene was a good resolve builder, Sakura getting rid of Assassin was fucking brutal and amazing at the same time. I didn't talk about this one at the start, but the chibi Shadow familiars that Sakura uses in this film were a completely new addition as far as I know, and they kind of stole the show each time they appeared. One literally touched Assassin on the ankle, and his entire body up to the waist (I think) just exploded. Fantastic way to end him. Back to Shirou prepping to go, and him seeing Sakura throughout the house as memories really drove home how much she means to him. Illya being a cute older sister too, seeing the three of them off.
Now we get to the spectacle portion of the show. I'd be interested to know just how much of the film's budget went into Saber vs Rider, because holy fuck it was ridiculous in a great way. Some will find how much of that fight was in slow-motion to be irritating, but I took it as a representation of how fast Rider and at points Saber were moving that it had to be slowed down to convey the action. There's not really much else I can say other than it was beautiful to watch. One personal point of vindication for me though was seeing just how well animated the environment was here; THIS is how you animate rocks exploding up from the ground and disintegrating into smaller chunks; FUCK you Apocrypha and its shit-ass attempt to convey that in the Karna/Sieg fight!! /rant over. Excalibur vs Rho Aius and Bellerophon was just about how I imagined it would be, and the swift follow-up of Shirou thrusting Azoth into Saber's chest was good to see. Was half-expecting to see some hesistation on Shirou's part before bringing the blade down, but not showing any was a much stronger and satisfying visual to me.
Rin vs Sakura matched up very well too. Again, the chibi shadow familiars appear and steal the show, before we get down to the Jeweled Sword looking just as good if not better even than an Excaliblast in many instances to me. I want to rewatch that part alone again second of all after Saber vs Rider again. Final part leading to Rin closing in on Sakura was done well, as was the end result.
Shirou arriving and moving in to free Sakura with Rule Breaker was... something. Maybe someone felt that it was needed, but I wasn't really on board with Shirou running across the cavern, dodging Shadow Ribbons and than leaping into the air OVER a pit of lava to land on the now-floating rock that Sakura was suspended on to free her. Chibi Shadow familiar's best spot appeared here soon after by transforming into a cloth/shroud/pick your covering word here, and than having its seven eyes appear OF COURSE on her boob.
Shirou vs Kotomine was what I was looking forward to most for the show, and I think I overhyped it in my own head too much. It was still a good visual showing, but something was off. I think it was the music choice for the most part; I was spoiled for years with Kotomine's theme from a church organ playing in the bit before the fight, and I didn't really like whatever instrument was playing it this time, maybe an oboe or something. No Light and Darkness theme that I could tell for their actual slugfest was a major strike for me too, but damn the slugfest itself was meaty and brutal, just as it should have been.
Illya scene to close the section here was very sweet and hit me hard in the feels when it showed her running into Irisviel's arms at the end. Ugh, I'm not crying, you're crying!
Epilogue was changed a bit to start with a monologue from Rin, but than transition over to Sakura a bit sooner than I would have liked. Maybe it's because Zelretch was already shown in the flashback for the Jeweled Sword, but not seeing Rin being grilled by the masters of the Clock Tower and him coming into defend her/take her under his wing was a small letdown. Rider in glasses is beautiful as always. Smallest cameo you could ever think for Touko, that's definitely not something that those who didn't know it was coming or at least hadn't see the KnK movies would have noticed as you only get about 3 seconds of her back as Rin and Sakura move past her in an alley. Small shame that. Seeing everyone go Sakura watching was fun, and I loved the small touch of Ayako recoiling away from Rider as she leaned down next to her.
Overall, Spring Song was a delight to watch, but... honestly I think it's probably the one I'll remember the least about beyond the major points and spectaclar fights. Presage Flower and Lost Butterfly just stand out more for me. Maybe it was the atmosphere like I alluded to at the start, but I wasn't as impacted throughout this film as I had been for the previous two while watching them. Would still watch again in the future, but it could have used more in some areas and less in others. Personal score at about 7/10