It had good sales:
comichron has it at #17 for November -- the only better-selling DC books are Batman, Justice League, and Green Lantern; not to put too fine a point on it it outsold Walking Dead and Avengers by about 20,000, and was only a few thousand behind My Little Pony #1 and the much-ballyhooed Amazing Spider-Man #698. Granted, its sales were most certainly boosted by the Death of the Family crossover, but it still outsold Batman and Robin, Detective Comics, Catwoman, Batman: The Dark Knight, Nightwing, and Red Hood (not to mention Batman Inc and Batwoman, which aren't part of the crossover).
It was also pretty well critically-acclaimed, for whatever that's worth -- I wasn't keeping up with it but consensus seems to be that, after a rocky start (mostly rocky because Simone didn't immediately explain how Barbara was up and walking around), it found its footing and turned out pretty good. Like most of the DC books, people liked what she was doing with it and didn't like the stuff editorial was forcing on her.
But hell, you know, even if it HAD been terrible, there's no fucking excuse for firing a beloved creator via E-Mail. Short of a Liefeld-level temper tantrum, anyway. (And even then, I was pretty much on Liefeld's side up until he decided to blame everything on a low-level editor and insult him by name instead of putting it at the feet of Warner Corporate, who I think are the ones who are really responsible for everything from the New 52 to Before Watchmen to Berger's departure to the Sandman prequel...okay, that last one actually might be pretty good.)
EDIT: Going through her Tumblr:
I am not giving up on the idea of a major trans character in an ongoing mainstream title without a fight. I want a clear, unambiguous trans character in a prominent, unambiguous and unapologetic role THIS YEAR.
So it doesn't sound like she has any intention of leaving DC -- or if she does, it'll be to go to Marvel. She's not planning on taking her ball and going creator-owned (at least, not exclusively; she DOES have a couple creator-owned books in the works); she's as intent as ever on being the person who reforms the industry from the inside.
I...have mixed feelings on this. I think she's done an incredible job so far and DC and superhero comics in general would be poorer if she put her talent to use on original, less-prominent characters. But there is a big, big part of me saying "Fuck them; let them all burn down and all the talent go creator-owned."
As it is, the most prominent trans character at DC is probably Shining Knight. And Paul Cornell has been pretty vocal in his support of Simone today.