I expect it's partly because I'm not familiar with Final Fantasy, so there were probably a lot of things I missed; but that's a problem in itself - movies should explain things to the uninitiated.
The plot (shallow as it was) skipped around all over the place, so I found it very hard to keep track of what was going on. The fight sequences looked like they'd been cut and pasted from a computer game (and yes, I *know* it's based on one, but that doesn't mean they need to keep ramming the fact down your throat). Also, I'm not a fan of the animation - hopefully they'll realise one day soon that their characters will look far more real if they actually give them the occasional physical flaw. (Oh, and the hair still looks like they're constantly standing in front of fans. The Final Fantasy world must have great air conditioning.)
Eh, they're all the reasons I expected you to come up with. >_> Which means they're pretty understandable.
I mean, obviously this film is going to mean almost nothing to those uninitiated into the world of FF7 (and while I haven't actually played the game much at all, I know the basic plot). But then you can hardly expect them to explain the background plot by attempting to sum up an 100+ hour game in a few minutes. Does an anime movie - like an InuYasha one, or (though you haven't seen it), End of Evangelion - have to cover the entire TV series from which it was spawned in order to be entirely self-contained? Of course not. We accept that you really have to watch the series, or in this case, the game, before tackling its film extension.
The action sequences...well, they're there to look cool, not realistic. Again, this is pandering to the original fans, who expect to be taken back to what was in the game...although I did think that Cloud using his Overdrive move to defeat Sephiroth was a little lame. >_> Then again, it depends what you're comparing it to. If you think it's trying to be like a Live-Action movie then yeah, it's all very much OTT. But if you (as I do) just take it as Anime in a different animation style, then the action sequences aren't too out of place. Hell, I've seen stupider stunts pulled just from watching one episode of Bleach. >_>
As for the animation style: I've yet to see ANY computer generated human beings that weren't immediately discernable as fakes, either because they were "too perfect", or their movements don't flow well enough, or often their skin just looks kind of...waxy. Until I'm led to believe that people are capable of animating entirely-realistic human beings then I'm not going to get on the back of those that don't. That being said, FF7AC is one of the best attempts I've yet to see...it certainly put 'Spirits Within' in its place... ¬_¬ And as for the hair: is it not, like, coincidence that a large proportion of the film takes place in places where there IS wind? Barren wastelands, at great heights, or just generally moving about a lot at high speeds. Their hair doesn't do that when they're just standing around talking inside. This probably comes back to the animation flaw of perfection, in that when they are in the wind their hair flaps about with perfect co-ordination, which can sometimes be a little unnerving.
I agree, all (human, anyway) CGI characters are horribly perfect, no matter who does them (although surely animators shouldn't use this as an excuse...they could always leap on the opportunity to do something really groundbreaking and give us some characters that look believeable).
But...I dunno. I just couldn't bring myself to care about any of it. Maybe if I knew a little more about Final Fantasy, it'd be different, but as it was, I was sitting there thinking "Yeah, OK, so there's this disease thing...and fanatic bishis...and an angsty hero...and the token cute child...oh, and now the bishis have kidnapped some children and are using them as human shields...and normally a scene like that would really grab me, but as it is...eh." When it got to that artsy scene with the phone falling through the water, I'd gotten so bored that I just walked out.
As for the hair...it moves in nonsensical ways when they're indoors, too.
The world's going to hell, we're all clapping along... - Rob Paravonian
All the artsy scenes involving water are Aerith's fault. FF7 fanboys are supposed to be going "waaaaa she DIED", being that she was the major love interest in the game, but then snuffed it. I couldn't care less about Aerith so I could have done without them too.
Luckily, Sephiroth is just about badass enough to make up for it. But then you missed one of the bishi larvae (well, it's what I call them) morphing into Septhiroth, so you wouldn't know. >_>
Animation student input: it is not impossible to animate hair properly. Take Monsters Inc, Sully, one of the main characters is xompletely covered in long hair, which having watched the movie several times, i can reliably tell you, reacts exactly as it should do to his body movements and the weather conditions. The thing about final fantasy is that the hair appears to be stuck in slow motion which makes it painfully obvious that its animated. result Pixar> FF.