The moral of Advent Children? "Hey, you should get a cell phone!"
Let me be the first to say that it left open a whole bunch of plot holes from FF7 (not the least of which is, why didn't the Lifestream eradicate all of humanity as a threat to Planet's existence? Unless we're supposed to believe that Aeris spoke on humanity's behalf or controlled the Lifestream herself, but there's not much direct evidence to support this) and opened up a whole bunch of new ones (so, wait, anyone can grow into Sephiroth if they just take a swig of Jenova? And Geostigma is just the body's overreaction to Jenova cells and oh wait every child in Neo-Midgar has it? WTF, mate?).
Oh, bullet-time effects. Like we've never seen that before.
Blatant fanservice, from start to finish, and I don't mean in the panty-shot sense neither. I mean, dude, the caption right at the start comes right out and says "This is for the fans, yo." Fans want to see all the characters from FF7? Okay! Fans want to hear the Victory Theme after a big fight scene just like in the game? You got it! Fans want Aeris to come back (even though she is dead dead dead like a dead thing)? Coming right up! Fans want to have another big fight between Cloud and Sephiroth while "One-Winged Angel" plays in the background? So let it be done!
And that being said? I loved it! Oh, so very very very pretty. I had a big silly grin plastered all over my face while I was watching it. And there were a couple parts I laughed muchly at (like Reno at the Healin Lodge, or basically Yuffie's whole bit on the bridge of the Shera). I mean, sure, if you look back on it with the canon, it doesn't make a lick of sense-- but remember, neither did the Escaflowne movie...
So, to sum up, I liked it, problems and all. ...This probably means that my taste is wholly in my mouth.
Oh, and I just posted interview questions, to those who asked to be interviewed.