Air's greatest weakness is that after a character's arc is completed, the character drops completely out of the series. While the girls do develop nicely within their arcs, it can be frustrating to see them disappear from the face of the Earth once their respective personal dilemmas had been solved. However, as with all other aspects of the show, Misuzu, Haruko, and Yukito are developed spectacularly, especially the former two. Their every quirk, fear, and neurosis is put on display, and their struggle to overcome such problems is magnificent and moving.
Most of the seiyuu work is quite excellent. Hisakawa Aya in particular does an excellent job as Kamio Haruko, especially in the final few episodes. Kawakami Tomoko of Utena fame comes off uncomfortably high as Misuzu in the beginning, but settles into her role quickly, and puts all of her ample talents into the conclusion. The only voice I did not like was that of Minagi Tohno, who is portrayed with a soft monotone, no matter what the emotion of the scene.
Although Air manages to rise above many flaws that seemed inextricable from its genre, it still is bogged down by a few others. Nonetheless, technical merit and sheer emotional power manages to elevate the series to a cut above the rest.