Animation: Great. Excellent combination of normal animation and CG. Just that some things could have been done bettter.
Sound: very good, like the other ST animes (and with the same seiyuus)
Story: Ah, the story.... It takes place when Oogami is still in Paris with the Paris Kagekidan. If this is the first Sakura Taisen anime that you see and you never played a Sakura Taisen game before you'll say: "Eh? WTF is all this about?!?!" followed by a lot of questions, and you won't understand a thing. But if you played the games (or watched the TV series) or managed to follow the OVAs, you'll understand everything (well, most of the things).
Character: Well, since this is only a short movie that lasts 85 minutes.... you cannot develop the characters perfectly. Anyway, they managed to develop the new character, Lachette, pretty well in this short movie.
Value: For a true ST fan, this movie is (or will be) a very important piece of animation that connects the old and the new characters (Sakura Taisen V, where Pattrick appears too).
Enjoyment: It's truly a great film worth rewatching several times, specially if you're a ST fan. If you're not, you still can watch the CG battle scenes, right?