This movie, while separate from the anime's plot, really delves into Inuyasha's, and some of Sesshomaru's, pasts, which I really loved, and it showed how these pasts made them who they are. That emotional aspect was done very well.
However, the beginning bit with the sword, while explained later, seemed a little convenient... Definitely a plot device to get the movie going, instead of seeming like a natural part of the movie.
I also felt like much of this movie was just fighting, fighting, fighting, hence why I gave it such a low score. I understand that there is a lot of action in the show, and thus there should be in a movie as well, but I got bored with all of the fighting, as I felt like they were just stalling to make the movie longer, instead of getting on with it.
I really loved the ending scene after the credits, though, and Rin was as adorable as ever.
Overall, the emotional aspects of the movie were great, but there was just too much time spent on pointless fighting for me to have really enjoyed it.
This movie was half enjoyable, half not. Most of the time, towards the end, I'd be facepalming about three or four times because of how stubborn everyone was being. I'll try not to reveal any spoilers as per usual, but there were some glaring inconsistencies with the movie (which I watched for the first time after re-watching the series).
Let's start with the basics, then I'll get into why I'm not giving this movie a high rating.
A sword called the Sounga has somehow made its way to the Higurashi shrine, and was being taken to be "aired out" by Kagome's family. It's then that the sheath, named "Saya", starts talking to them and the sword then takes off on its own where it encounters Kagome and Inuyasha alone in a park.
Inuyasha's attempts to get the sword back to the sheath doesn't work very well, as it brings out his demon side, and instead he manages to at least get it back to the Sengoku Jidai. However, he has trouble controlling the sword and keeping it from taking over his mind.
In the meantime, Sesshoumaru keeps remembering his father asking him if he has something to protect, and when he senses the dark aura of the sword, immediately goes after it to claim as his own.
Nothing really new to see, here. We've got all of the standard characters, though Naraku does not make an appearance in the movie. Instead, the main antagonist is the sword Sounga itself.
Rin gets to actually do a little more than usual in this movie, which is a nice change of pace.
The movie also focuses on Inutaisho, Sesshoumaru, and Inuyasha (the latter two, specifically).
The movie started out enjoyable, and certainly had its moments, but it centered very squarely on Inuyasha and Sesshoumaru, as well as a bit on their pasts. While this certainly brings up the rating, as a lot of things surrounding their pasts are ambiguous at best, the other characters don't play much of a role until the final battle.
In fact, Sango, Miroku, and Shippo barely get to do anything until the climax. Though I love team-ups between "bad guys" and good guys, and it was really neat to see Jakken and Rin team up with Kagome and the others, the battle was outclassed by the fact that the Kazaana was pretty much rendered useless and the high focus on Inuyasha and Sesshoumaru's attempts to fight their way through the climax.
The movie also made quite a few giant errors. I might dip a little into spoilers to cover them, so you have been warned.
The first error is that Saya is supposed to guard Sounga for 700 years. He guarded it for 200 years, and the other 500 disappeared when the sword was flung into the Bone-Eater's Well. It's even brought up in the movie (via Shippo's question) of why that accelerated Saya's age but doesn't affect Kagome nor Inuyasha when they travel back and forth.
The question is never answered. For Kagome, one could say that it's due to her miko powers, and Inuyasha is a hanyou, but both are a fairly weak argument.
One of the biggest issues I have with the movie is a point where the antagonist gets into Inutaisho's gravesite...which should be impossible to do without huge preparations. Naraku had to do quite a lot to get in since he didn't have the black pearl. I suppose the argument is the type of sword Sounga is, but that just makes it rather convenient.
Most of the other "errors" are instances in the movie which makes you go "why didn't they do that in the first place?". There are at least two occasions (not going to go into details to avoid spoilers) where, if the characters had just performed a single action at that point instead of much later on, things wouldn't have gotten to the point they went to.
Then again, one of the biggest mistakes in that department could have potentially ended the movie right at the start, but to me, it's poor writing to have something in there which, if used at the right moment, could have changed the entire course.
As in, at the beginning instead of during the rising action. Seriously, if this action was performed even five minutes in, there would probably have been no movie. For such a plot device to just hang around like that for at good portion of the movie is bad writing no matter how one tries to justify it.
There's also little in the way of conclusion; I'm not going to touch much on this to avoid spoilers, but I don't like the way it was wrapped up. During the battle, everyone could have died, and one character nearly did. Five minutes later, that character is fine. Not to mention that we see how exhausted Inuyasha is by the time of the falling action, but none of that is apparent moments before the credits.
The teamwork and even focus which was in the first two movies just didn't seem to be there in this movie. There are also times when the characters are drawn a little oddly, and other times when it was difficult to tell what was going on...so I docked points in the animation department. Perhaps some people will like the more "modern" way it was drawn, but I grew up with Inuyasha...I was reading the manga before "Final Act" had even started production. I was fine with the character designs and animation in Final Act, but this movie was just a little awkward in some places.
Still, facepalm moments and glaring errors aside, it was an enjoyable movie. I wouldn't say it was one of the best, as the first two were certainly better, but it wasn't the worst anime movie I've seen, either.
This is the third Inu Yasha movie, taking place after the hero has learned the diamond shard technique. Although still a filler movie, it is offering lots of canon information that was never used in the main series but is otherwise not contradicting anything either. So it is a sort of a must-watch to anyone interested into the past of Inu Yasha and his family, as we see the last moments of his parents and how the third powerful sword his father was using was taken over by the hatred of a mortal who was in love with his wife. In the present, that is more than enough for both Inu Yasha and his brother fighting both the sword’s demonic powers, as well as each other to see who gets to wield it.
The emotional engagement is simply great, as the whole conflict is based on twisted love and not the usual megalomaniac villains who want to take over the world. For once Inu Yasha’s dark side is not used just for the sake of cheesy drama but as true reason to become a full demon. Plus this movie has by far the largest amount of action you can find in the whole franchise. It literally raises hell itself and the affected areas turn to a thing of horrors. Combined with far better production values than the tv series, you get a more than good action/drama movie.
The ending though is kind of a cop-out and ruins the otherwise interesting build-up. It was more than obvious what would the solution be to the problem. But whatever, those who are fans will appreciate the fleshing out of the protagonist, while those who are not will get kicks out of the epic level fights.