Where do I start with this one? The Shippuden movies are very hit-and-miss, and that continues on for the later movies as well (which I actually saw before this one). This movie has so many glaring errors that I was either scratching my head or groaning through it.
One of the only good parts is that this movie wasn't one of the typical "everyone gets super quiet during talking scenes and then the volume hits max decibels during battle/tense scenes". There was a little of it, but it wasn't as bad as some of the other movies.
Story
Your typical Orochimaru-type bad guy who is trying to absorb five major bloodlines in order to become immortal/all powerful.
The final bloodline he has yet to grab is apparently the Sharingan from Kakashi, and so he activates a mark he had put on Kakashi (who convinces Tsunade to let him go before his mind is taken over) to pull the man to him. Naruto (as well as Sakura) doesn't take that news well, and goes after him.
Meanwhile, the antagonist somehow made a projection which was seen all over the nations where he announced that he is a Konoha ninja and is going to become more powerful than all of them and start the Fourth Ninja War.
This prompts Nations to prepare for war, particularly Leaf and Sand, because for whatever reason they think that Konoha is behind the entire thing (I'll get to why this is stupid later on).
Characters
Holy OOCness, Batman!
The antagonist...well, he's just another generic Naruto bad-guy doing bad things in an Orochimaru-like way (experimenting and chimeras). His minions serve little to no purpose except to be a distraction. There's not much more to say on his character.
Naruto was on point for the movie, as he usually is. All the other characters were pretty much as-is...
...except for Shikamaru. While I can sort of understand the rigid thinking he did during the movie, Shikamaru is supposed to be someone who can think of dozens of possible steps and outcomes, yet we're supposed to believe that sending Kakashi to his death for the sake of Konoha was the only solution possible?
Though he did gain a lot of maturity by Shippuden (and particularly after the Akatsuki incident), I wouldn't have believed Shikamaru would act the way he did if I didn't see it in the movie.
The others (particularly Lee) seem to understand what Naruto is trying to do when Naruto gives them the famous line about "those who disobey orders are scum, but those who abandon their comrades are lower than scum". They even join up to hold back the minions to allow Naruto, Sakura, and Sai time to reach Kakashi before he can go ahead with his suicide plan.
However, on the final encounter, they still encourage Shikamaru to go on ahead to presumably stop Naruto...which totally doesn't mesh with the understanding they had just moments ago.
Gaara was also pretty OOC in this, as he knows and believes in Naruto and wouldn't have stood in Naruto's way if he was in character.
Overall
I did like the theme of the movie, I'll give it that. The characters are forced into a situation where they have difficult decisions to make; in Kakashi's case, he decides to sacrifice himself for the village...in Tsunade's case, she has to agree to it......and, of course, a situation where the characters are forced into actually deciding between the "mission" and "comrades"...
...if the movie didn't totally screw it up.
My first major issue with the movie is Shikamaru's attitude and position. While I can understand some of his mentality, Shikamaru wouldn't sacrifice a comrade to protect something else. This is evidenced by his very first mission as a chuunin, the doomed Sasuke Retrieval mission.
In the end, he felt horrible that he had to leave his friends behind one by one to fight against ninja they were outclassed by, and, in tears, swore he would never allow such a thing again when they nearly died because of it.
Shikamaru even said he would stop Naruto even if he had to kill him, which goes against everything the Konoha 11 stand for. It also makes no sense character-wise, nor does it make sense mission-wise. This isn't the same as the Sasuke Mission, where Sasuke voluntarily DEFECTED from Konoha to join up with Orochimaru. Rather, this is a case where Naruto and Sakura disobeyed orders to save a comrade, not join the enemy.
In conclusion, even though Shikamaru knows he has to protect the "king", he should have been able to think of other possibilities and outcomes, and not be so dead-set on Kakashi's sacrifice as being the only way to stop the war...
...which brings us to the next point.
This was a huge plot hole and failing of the movie, and that was the fact that somehow, because some random ninja from Konoha declared war, everyone got it in their heads that Konoha itself was declaring war, and they should all go to war.
Um...say what, now?
There weren't even any attacks on the other villages to prompt the others into action; are we supposed to believe that the leaders of the ninja world are so stupid that they would believe that the actions of a single ninja (no matter what village that ninja is from) reflects on the entire village?
That just because some (obviously rogue) ninja, with no hitai-ate and could have very well have been lying to the other nations for all they know about being from Konoha, declares the start of the Fourth Ninja war that they should just blindly start attacking each other?
Not to mention that the major conflict in attack was seen between Konoha and Suna...who are ALLIES. Gaara and Tsunade were going to meet up to (presumably) discuss the situation, and suddenly a war is starting between the nations? What about the other nations who have less-than-friendly terms with Konoha (like Earth and Lightening)? Shouldn't they have been the first to point their catapults at Fire country?
It makes no sense! The only explanation to that plot hole is that everyone in the ninja world is a freak'n idiot.
That would certainly explain a lot about the movie, then. A couple of the fight scenes were interesting, though how Naruto defeated the antagonist doesn't quite make sense (I'm not going to go into it for the sake of spoilers) either...
Aw, heck...the entire movie doesn't really make any sense besides keeping to the theme of the two bells and the "those who abandon their comrades are worse than scum". That's probably the only thing the movie got right.