NOTE: Please keep in mind that this review is old, so while some editing has been done to make it read a little more timelessly, a lot of it is obviously dated. As such, where some things may be noted as 'spoilers', they probably no longer are.
And now for the final review on the Air franchise, I give you Air: The Motion Picture. I'll go ahead and warn you now - there may be slight spoilers in this review, as it'll be hard to comment on the movie without discussing the differences between it and the series. However, I'm going to do my best to keep them to an absolute minimum.
For starters, you'll notice that the art for the movie is different from that for the show. In a lot of cases, this is simply because of a higher funding for the animation studio, but this time it's because the animation was from a different studio entirely. While the TV series and the OVA were done by TBS Animation, the film was done by Toei, of Dragon Ball and One Piece fame. It's not that the animation is bad, it's quite beautiful really. However, the basic art-style is completely different...to give you an example, here's Misuzu in theTV series, compared to her in the movie.
Now, the other main difference between the show and the movie (without delving too deeply into the story itself) is the overall feel to said story. Whereas the show felt more like a mystery filled with drama, the film version feels a lot more like a love story. Which version you like more will probably depend most on which version you watch first, as I have to say I found the show much more enjoyable.
That's not to stay that I didn't like the motion picture - I loved it, it's definitely a must see for anyone who's seen either the show or the OVA. Hell, it's even a great film if you haven't seen anything of Air before. I just can't classify the film as a must-see for everyone, like I did the show.
There's not really a whole lot more I can get into without spoiling some of the finer points of the story, but I will give you a heads up - keep your eyes peeled for small cameos by most of the other girls from the series, as well as the cute little puppy Potato. They're small and relatively pointless, but it's a great way to still show them.
Overall, the film isn't anywhere near as amazing and landmark as the series version, in this humble fan's opinion, but still a film you should give a look-see.