It's kind of boring. The second half's more entertaining than the first because we can enjoy the sight of Japan blowing up Americans, but even those action scenes end up dragging. Historical accuracy redeems it, though.
It's a history textbook rather than a movie, basically. Darryl F. Zanuck at 20th Century Fox wanted to make an epic about "really happened on December 7, 1941". Production took three years and involved equal amounts of Japanese-language footage made in Japan and English-language footage made by Fox in Hawaii. The two would be interleaved. The Japanese director was going to be Akira Kurosawa, who spent two years on pre-production and script development for it, but he wasn't a comfortable fit for a big collaborative project like this and it ended up with Toshio Masuda (Space Battleship Yamato) for the dramatic scenes and Kinji Fukasaku (Battle Royale) for the action.
The problem with the film as a film is that it's not about its characters. We'll eventually become familiar with a few of them through repeated exposure, but no one particularly matters and there's no tension or dramatic focus. There's no hero, heroine or loyal buddy. Women are nearly (although not completely) absent. Instead it's the story of a military episode. The Japanese bomb Pearl Harbour. (Spoiler.) That's it. Until then, the film is full of actors playing real people doing what they really did, which means day-to-day maintenance, security reports and committee meetings. This isn't quite as boring as it sounds, but it's not far off and it goes on for a long time.
The film even has an intermission. Normal films, even long ones, don't feel the need for intermissions. You'll be glad of it, though, because it's a sign that you've got the duller half of the film out of the way.
Because the history is faithful, it justifies its existence. It's like a history documentary, except that they spent 25 million 1970 dollars on it. You've got to be a military hardware nerd or to live on Hawaii to be able to spot any flaws, while footage from the film has since been used in many other films and TV series for its accuracy. You also know that they're doing it for real. No CGI in 1970. The dogfights are less exciting than, say, Star Wars, but George Lucas didn't have actual WW2 fighter planes going at each other overhead for the cameras. The planes, the ships, the explosions... it's all there, on the screen. No need to wonder where the money went.
The film won an Oscar for Best Effects, by the way, despite a dodgy bit of matting when that student plane nearly flies into the Japanese attack formation. No arguments there.
These days, it's amusing. The Americans' incompetence is funny, although understandably that's not the spirit it was taken in at the time. I loved them being unable to put up their radar because they need permission from the Hawaiian National Park and the Wildlife Preservation Society, although in fairness it happens eventually. The commander who wants confirmation for everything. The telegram. "Is it marked urgent?" "No." It's like black farce, although in fairness there's one big debatable decision on the Japanese side too. Well, technically two if you count the obvious one of "is it really a good idea to declare war on the USA while at the same time trying to enslave the entire Far East?"
Some of the characters manage to come alive. The Japanese ambassador in Washington gets some wonderful material and your heart will bleed for him. (He didn't want war and he was trying to do the right thing.) Several Americans get enough screen time that you can feel their frustration. There's a super-smiley Japanese pilot, while I liked the near-cameo for the man nicknamed "Gandhi".
The English-language acting is a bit frayed around the edges. There's what one of my drama school teachers used to call "a sad bus queue", while I wasn't impressed with the delivery of, "You wanted confirmation, Captain? There's your confirmation."
As for the Japanese scenes, they're making them look humane, civilised and even likeable. There's cultural colour in the banzais and the shrine, but don't expect even the faintest hint that some of these people might be war criminals. That'll be because we're dealing with the air force and the navy, who do a professional job in a high-tech environment and don't have to kill people except at long range. As for the Americans, it's interesting to see how they're always trying to negotiate with the Emperor, when in fact the Japanese power structure is far subtler than that and the Emperor's best attempt at influencing events is to read a poem to the Imperial Conference. (He really did read that poem, by the way.)
The film hit it big at the Japanese box office, incidentally, but in America was seen as a flop. This is curious because it took a smidgin under 30 million domestically and was the ninth highest-grossing film there of the year.
Overall, it's stodgy and somewhat indigestible. However I admire its verisimilitude and for that reason it's worth watching. From a Japanese point of view, it ends on a correctly disquieting note and will have you wondering how you lost the war to these clowns. From an American point of view, it's a horror story. For anyone else, it's a black comedy with about an hour and a half's padding. I wouldn't recommend it too hard, but it's not without interest.
"Get that guy's number, Dick. I'll report him for safety violations!"