I am enjoying Mai-Otome quite a bit, although not as much as I enjoyed My-HiME.
Mai-Otome, also known as My-Z-HiME, is sort of a second season of My-HiME, except in an alternate reality sort of vein. Most of the characters from My-HiME return, with a few differences, although the show stars two new characters that only had brief cameos in My-HiME: Arika and Nina. The third star of Mai-Otome is Mashiro, who is quite different from her My-HiME counterpart (for the better, I think).
Wisely, neither Natsuki nor Shizuru are much different personality-wise in their new Otome roles.
Also, strictly speaking, I think one could interpret Mai-Otome as occuring within the My-HiME universe and timeline, just three hundred years in the future, and arguably still kinda on schedule. Those of you who saw My-HiME should know what I'm talking about.
Through 13 episodes, Mai Otome has yet to turn into the wonderful "magikal girls betraying and killing each other" dramabomb that was My-HiME, but this development is expected shortly. I'm looking forward to it, and the tragic Yuki Kajiura music that is bound to accompany it. I just hope the ending of Mai Otome is much more downbeat than the ending of My-HiME.
In fact, regardless of what happens this season, I motion that Sunrise commission a high-speed three-hour My-HiME anime opera composed by Yuki Kajiura that ends in spurned lesbians tearfully killing their loved ones and utter tragedy and whatnot. It'll be totally radical.