It's excellent. I really liked it. It's a fairly straightforward kiddie film, but it's got memorable baddies, striking fight scenes and good characterisation for the Yes! PreCures (from their first season).
I've just finished watching all of Yes! PreCure 5 (Yes! 1) and its sequel season of Yes! PreCure 5 GoGo! (Yes! 2). It's basically okay. It has plenty of good, solid material, but also some factors that for me knock it down a bit. Here, though, I didn't have to worry about any of those.
Firstly, the characterisation. This is a Yes! 1 film (released between ep.38 and ep.39). Thus, in characterisation terms, we're at a sweet spot. Enough time has passed that there's plenty of characterisation for the film to pick up on, but not so much that we're in boring GoGo territory. Thus, for instance, Komachi enjoys telling a scary story so much that she frightens Rin... and, frankly, us too. There's a moment of Rin teasing Karen, because they're Honoka/Nagisa clones and so it's nice to allow them time together. Rin gets to be sporty, Milk terrorises teddy bears (and bizarrely thus earns their respect), there's a reminder of Early Karen's aggressive solitude, etc. This is all good.
We even get relationship tease for Coco-Nozomi and Nuts-Komachi, even though that's about to get thrown under a bus in GoGo.
As for Nozomi, this is a strong outing for her. She's not being a comedy character, unfortunately, but she gets good material with Coco (who claims to have spidey-sense to detect her). She gets to be game-changingly perceptive, in a thoroughly Nozomi way. She wins through beautifully idiotic optimism. When all the PreCures have to fight dark reflections of themselves, Nozomi befriends hers. The film ends up exploring her emotional depths, in a way that feels true and satisfying.
Frankly, it's just nice to return to Yes! 1. Kowainaa are better than Hoshiinaa! I'd missed Urara's crazy spinning spiral hair transformation. It's like a breath of fresh air to return to the Yes! 1 transformation sequences, which are the shortest in the entire franchise. (GoGo's, on the other hand, go on way too long if chained together.) I'd also forgotten how good Yes! 1's theme music was, especially since it tends to be the (also admittedly good) Yes! 2 theme song that gets used in All Stars reunions.
Then we have the villains. There's a mirror motif. Mirror mazes, mirror doppelgangers, infinite reflections in double mirrors, etc. Naturally the villain has mirror powers, which makes him pretty intimidating. There are scenes here that qualify as kiddie horror. As for the Dark PreCures, their nihilism is mildly chilling. "Why are you smiling?" (She genuinely doesn't understand.) "Friends are a pain in the neck, aren't they?"
Then, in addition, we have the movie-quality fight scenes. I know, I know, fight scenes shouldn't matter... but this is PreCure. What's more, it's Yes! 1 PreCure, before it became pathetic in GoGo. Here, though, they're cool. Nozomi vs. Dark Nozomi is a HELL YEAH. Wow. Those were impressive power blasts. All the girls get striking fights, though. Karen gets a lightsabre fight scene, although admittedly this does make one wonder why she didn't do that more often in the series proper. Oh, and the villain gets an awesome demon transformation.
Incidentally, this was the film that introduced Miracle Lights, those silly torches that got handed out in cinemas to all the children, to wave when the characters on-screen told them to. They're ridiculous and absurd. I love them. Thinking about it, they're a bit like English panto traditions, where the children are encouraged to hiss and shout out "he's behind you".
This is a surprisingly strong film. It has tragedy, with the death of a sympathetic character and the impact this has on Nozomi. (Quite a lot of PreCure villains might perhaps have died, if you think about it afterwards, but this isn't usually made explicit at the time. This isn't the kind of franchise that says the word "dead" or has people standing by gravestones. Here, though, we see a character's body disintegrate and then the villain says that he's disposed of someone who'd stopped being useful. That's not really open to alternative interpretations. That's death.)
I enjoyed this film as much as almost any episode from its parent series. It's so good that it elevates all of Yes! 1. (That's not a dizzyingly high bar, but I'd assert that it does.)