Yes, there are spoilers. either keep reading, or don't.
Mister Freeze was an odd case in Batman's Rogues Gallery. He never technically appeared in the comics before the TV series - the character appeared once, and was named Mr. Zero. But as it did for so many villains, the series made the baddie a marketable name, and he began appearing in the comics. He was still a fairly one-note character; as a result of an lab accident, his body temperature was reduced to below zero, and must maintain that temperature, or die.
He was played by three different actors on the series: George Sanders, Otto Preminger and Eli Wallach. Indeed, when you add in the various voice actors and (ecch) Arnold Schwarzenegger, he holds the record for the villain played by the most different actors in all the various media.
When Batman - The Animated Series came along, Paul Dini did something that would soon become a stable of the DC Animated series - he made Mr. Freeze more awesome than the comics ever had. His name was now Dr. Victor Fries, and his accident was due to a series of experiments to restore his wife, Nora, who he had placed in cryogenic suspension after she contracted a terminal disease. He was still a villain, and a foe of Batman, but adding this twist to his origin gave him a facet of pathos, and quickly became one of the breakout characters of the new series. He got a direct-to-video movie all his own, and by the time Batman Beyond came along, they effectively turned him face, curing his malady (temporarily) and giving him a chance to vindicate himself.
Many times over the decades, the ideas from other media were folded back into the comics. Much of Superman's mythos, up to and including Kryptonite and flight, came from the radio series. Mr. Freeze's animated origin became the origin in the comics - Nora was folded into continuity, and with it the pathos of the character. Even as the interpretations in later cartoons took other directions, the one from Batmanimated remained the standard in DC's and the readers' eyes. It's even the one they used in Batman and Robin, with...shall we say...debatable results.
Mr. Freeze has been brought back in the new 52, with a more hard-ass design and more (I apologize in advance) cold-blooded attitude. And with the return, they've tweaked the origin again. Dr. Victor Fries' marriage to Nora is a fantasy. Yes there is a woman named Nora who he's been trying to cure and wake up, but her name is Nora Fields, and she was frozen in the twenties, the first human ever to undergo the radical process. Fries, already unbalanced from a childhood accident where his mother nearly died after falling through the ice, projected a relationship onto the woman, who he had even written his first research paper about. His whole relationship with her has been a delusion all this time, and Batman confronts him with the fact, causing a violent reaction.
Now I admit, as I read it, I was impressed. It was a nice surprise, and did a good job of surprising me. It's a good example of the "Everything you know is wrong" type of story that have become so popular since Alan Moore did it to Swamp Thing.
But after the story was over, I realized that while it was a good story, the new baseline of the character, while different, is not better than the previous. Freeze's connection to his wife gave the character that bit of humanity that made you feel for him. As for his actions, you found yourself quoting Chris Rock's joke, "I wouldn't DO it...but I understand". But the new story pretty much makes him Just Another Nutcase. Like so many Bat-Villains, he has an unnatural fixation on something (in his case, the cold), based on events from his childhood. That fixation, combined with a traumatic event (in his case, but not always, giving him powers), causes a psychotic break that results in him turning to a life of crime. It's a shame that he thought the nice ice lady was his wife, but it was only a delusion, and now that it's brought to his attention, is no longer the case. So he's pretty much back to being a generic gimmick villain. He's not as different from Scarecrow and Penguin as he used to be.
Now there no reason they couldn't change their mind back. Heck, they could say that Batman just plain lied about it not being his wife, just to mess with his mind and generally be a douchenozzle. But that would require coming up with a good reason to do so, and those "no he didn't" stories, often come off weak, and rely mainly on David's Law, and the reader accepting a weak story because it gives them the result they want.
I've no idea how much they plan on using Freeze moving forward - his plan in the book was to get outta Gotham, though his capture and return to Arkham put the kibosh on that. He's certainly got more of an edge to him now, but as I say, the problem, without that motivation driving him, he becomes (to me at least) less interesting a character. Not all change is good - sometimes it's just... loose change.