The Astonishing X-Men series is a critically and fan acclaimed series for good reason.
For 25 issues Joss Whedon and John Cassidy are left alone to create some epic stories. Whedon's dialogue is reminiscent of the best elements of Buffy, while heavy attention is paid to the characters. The story arch itself is also well done; Whedon introduces the idea of the "Mutant Cure" and then plays out the emotional repercussions. The movie X-3 is a pale imitation of this Wheddon plot.
And then there are John Cassidy's drawings which are smooth, clean and crisp. Although the characters look clearly super-heroic, the drawings are subtle and not over exaggerated. The fight sequences are well crafted in three dimensions and attention to detail is made to their placement. And the covers! The covers are iconic and just plain awesome. Brian Bolland fans should appreciate them.
Together Wheddon and Cassidy created 25 issues of wit and charm.