To my astonishment, there are people who like this film. At first, I thought it was risible. I got booted out of it hard by the film's first ten minutes and it took me about half an hour to claw my way back in.
It's okay in the end, to be honest, but that's... um, a far cry from the TV series (and, I presume, the visual novel).
The art's uglier than I'd expected, which isn't what one might expect from a movie. Hurm. Ah well. Anyway, we begin with a much more depressed, negative and nihilistic Tomoya than you might have expected from the TV series. He's utterly without motivation. He's going to school for lack of anything better to do, unless perhaps it's the desire to put distance between himself and his dad. He hates his dad. This is quite good, actually. It's a more dramatic starting point than the TV series had.
I'll even be generous and overlook my dislike of the film's version of Tomoya's father, who's being characterised in much more obvious hues. The TV version always seemed well-meaning, but he was so passive and flawed that Tomoya's attitude towards him didn't seem unreasonable. He also had a drink problem, could hardly hold down a job and was capable of committing crimes. Here, though, the moral of the story is much more obvious from the beginning and Tomoya just looks a bit of an idiot for being such a dick to a father who's worked himself to the bone supporting them both. Okay, the shoulder incident is regrettable. He's got some sympathy points there. Nonetheless, though, personally I didn't see much subtlety in the portrayal of that relationship. Tomoya's wrong. End of story. Dad's big self-flagellating confession hasn't really been demonstrated by any bad behaviour we've seen from him, whereas the root cause for Tomoya abusing his dad for years is... a bad dream. No, I'm not joking.
That said, though, different doesn't mean bad. The movie's still telling a perfectly valid story about problematic father-son relationships. It works quite well. There's nothing wrong with Tomoya being an idiot. Teenagers do that. However it's a more predictable story than the one in the TV series, with a more one-sided use of the characters. Tomoya's a moody brat and his dad's an underappreciated saint. I exaggerate, but not by much.
Anyway, we were watching the start of this movie. Tomoya's walking up the hill. Nagisa's there. I remember that. What's different here, though, is that Tomoya has absolutely no interest in anything (e.g. Nagisa) and certainly isn't trying to help her or talk to her. He's this surly lump who trudges past. In the TV series, he's supportive. He's got no idea who she is and he's basically just passing the time of day, but on seeing this girl standing on her own, he still goes up to her and advises her to do things like "find other fun and happy things" and "eat in a classroom with your friends."
Here, though, the Tomoya-Nagisa relationship starts with a needy, clingy girl glomping on to some boy who was passing. He's showing no interest in her whatsoever and indeed appears to be actively pushing her away. Nagisa, though, is a human leech and won't let him out of her sight. There's a word for people like that.
We now get some annoying, cartoonish comedy at school. Sunohara improves later, but his first scene made me want to smash faces in with bricks. Him and his teacher, basically. There's an occasional tendency for boys in this film (Sunohara and very occasionally Tomoya) to leer and walk like Ataru from Urusei Yatsura.
I didn't buy it. I was bouncing off the film. I couldn't get in. Theoretically I can see, for instance, that the emotional development of this extreme Tomoya is more dramatic than that of his TV equivalent, but all I was getting from the film was annoyance. I couldn't see why Nagisa had laser-targeted Tomoya, which is fatal in a film that's focused almost entirely on the two of them. (The other girls get cameos at best, although we see quite a lot of Sunohara. No Fuuko! No Fuuko! No Fuuko!)
A more imaginative script might have used this as an opportunity for characterising Nagisa, e.g. she'd realised that he'd shut down emotionally and so is doing all this to draw him out of his shell. She'd be the one trying to help him. This would fit well, since Tomoya does indeed end up getting humanised, and would also be a pleasing reversal of formula.
However the film hasn't thought to do any of that, so instead Nagisa's just a self-obsessed and mildly retarded stalker.
Things improve, though. The Sunohara-Tomoya relationship is fun. Sunohara's antics can be amusing and the film has a better lead-in to him getting beaten up by a girl. Yes, he can look like a rabid monkey when overexcited, but I usually found him entertaining. (The "smash his face with bricks" urge only came up once or twice.) The film's middle third is perfectly acceptable, then the last third is doing the darkness of After Story. This is okay. It's quite good. On an emotional Richter scale, it's a cupboard falling over while the TV series would have flattened a good-sized city... but hey. It's a decent attempt at telling a powerful story, despite having almost none of the TV series's build-up or breadth. It works. It didn't make me cry, but there's nothing much wrong with it.
There's also no magical ending, which will admittedly have pleased a lot of people. Tomoko for one. Personally, though, I think this raises story issues. The film has stylistic touches like the semi-magical storm of cherry blossom petals and plot points like Tomoya and Nagisa sharing the same internally consistent dream for years. (I liked the Pinocchio imagery in Tomoya's version of that, by the way.) In other words, we still have some magical build-up. It's just not leading to a magical pay-off. Sort of. Except for a fleeting moment. However this begs the question of what the hell we're supposed to think the shared dream meant.
I liked the music, although my heart still says they've got the wrong tune for the Dango Song. Quite good, but wrong. They've also mostly kept the same voice cast as the TV show and visual novel, except for a new Tomoya. This means more Kikuko Inoue, which is always good.
Would I recommend this? No. It's not actually that bad by the standards of anime movies, but that's hardly glowing praise. The TV show is astonishing. The movie isn't bad if you can overlook some issues. There are better ways of spending your time. In fairness, though, it's quite deft in how it cuts out almost all the characters and stories from the TV show's first two-thirds. There are people who liked that. (It manages to feel quite natural and organic at that length, despite being so abridged. The pacing's good.)
Watch it, maybe, if you're curious about Clannad but know you'll never get around to watching nearly fifty 25-minute anime episodes. Be warned that it's a pale shadow, though.