I know a lot of people have never really liked the character, but I've always have kind of a soft spot for her. She was probably my favorite WCIII character to play, and she is certainly one of Blizzard's better attempts at a strong female. She's always had her annoying points, but a character that no one dislikes is probably a character that no one is particularly going to like either.
In WCIII I saw Jaina as having been written as a foil to Arthas. Both characters were intelligent, strong willed, and emotional; but Arthas took these traits to extremes in a way that eventually led to his corruption, whereas Jaina tempered them with with wisdom, compassion, and a willingness to take advice. She was also an extremely intuitive character, whose "instincts" tended to be very good. These traits served her fairly well, and by the end of the game she's shown as a decisive, confident leader whose troops are willing to follow her into creating and entirely new country on Theramore Island.
We know from source material and in game stuff that she was born the second child of the leader of the City-State of Kul'Tiras (the Grand Admiral), that she was born with a powerful affinity to magic that led her becoming one of the few female wizards of the Kirin Tor, and that she and Arthas had some sort of thing going on prior to WCIII. We know that she reject Arthas before the Culling of Strat, because she refused to take part in the mass slaughter. We know that she was smart enough to see the threat of the Legion, and brave enough to lead her people in toe to toe battle with the most powerful destructive force in the Universe. We know she founded and now leads Theramore, and that her devotion to laws and treaties of Theramore are sufficient that she was willing to let her father die rather than betray them.
Now, ICC. WTF is up with her? First of all, she's suddenly obsessed with Arthas. She rejected him like ten years ago, before he was even corrupted, because she couldn't countenance his actions. She's shown no particular sign in those ten years that she regretted her actions any more than anyone else thinking back sadly on a failed relationship. Arthas: Rise of the Lich King certainly implies that she feels kind of guilty about the whole thing, but she's not really let that affect her actions in the last ten years. She's spent those ten years doing anything and everything BUT looking for Arhtas, trying to find out hat happened to him, or trying to redeem him. Yet now, suddenly, Arthas is her all consuming passion. She'll sacrifice anyone and anything to get to him and try to redeem his soul. Seriously, where did this come from?
Plus she's suddenly unwilling to listen to anyone or follow her instincts. Tirion, Uther and her gut all tell her that Arthas is gone, but she has to go have a quick convo anyway? The woman who took half her father's fleet across the unknown ocean, to a continent no one knew existed, on the advice of a guy who can turn into a crow she's never seen before, simply because it "felt right", is suddenly unable to trust her gut? Love makes people do strange things (though you'd think if she loved him so much she might have wandered out to Northrend before now), but it rarely completely changes how someone thinks.
Then there's the way she deals with the whole thing. She's a decisive military commander and one of the most powerful (if not the most powerful) Mages on Azeroth. She personally commanded, from the front, the human forces in the battle of Mt Hyjal. She's gone toe to toe with a demon lord (possibly THE demon lord, depending on whether you consider Saragas a demon or something more) without flinching. And she stands there looking weepy while that scrub Tyrannus kills her soldiers and raises them as undead? Really? Like some untried Lieutenant trying to find her ass? And she doesn't even think to have her people take cover when Sindragosa flies up to kill everybody?
Finally there's the matter of her personal history and her dialog in both HoR and the ICC raid.
"Frostmourne, the blade that destroyed our kingdom."
"Our kingdom"? What Kingdom? Kul'tiras is still there, and it's a city-state not a kingdom, so she can't be talking about her place of birth. Dalaran was beaten but not broken by the Scourge, and is also a city-state not a kingdom, so she can't be taking about the place where she trained and served. Theramore wouldn't even exist without the Scourge and Legion invasion, and is ALSO a city-state not a kingdom, so she can't be talking about the nation she founded and has shown herself to be utterly loyal to. What? Lorderon? A place she *visited* a few times? Seriously? Don't get me wrong, I'm sure she'd feel the tragedy of Lorderon's fall, and feel it keenly. Had things been different, she might have one day been queen there, but it's no more "her" kingdom than California is "my" state because I spent a few months in Silicon Valley a couple years ago.
"It was nothing, your majesty. Just... I'm proud of my king."
Her king? She's the founder and ruler of a full member state of the Alliance. She refused to surrender sovereignty of that nation even her own father, to the point of letting him die rather than give up Theramore's independence and treaties. She regularly goes her own way, even to the point of physically ending the fight between Varian and Thrall in the Undercity against "her king's" expressed wishes. Now suddenly he's "her king"? Her friend? Sure. A fellow ruler? Definitely. Even first among equals as the leader of the Alliance? Yes. But he's no more her king than Magni Bronzebeard is.
I dunno. I just hate what they did with her in this patch. She's always been a bit emotional (which Blizzard seems to require in its female characters), but she nearly always lets her head rule her heart when it's important. It's like they needed a character to do and say certain things, couldn't find one, and dressed up an entirely new NPC in the clothes, name and powers of Jaina Proudmore. Is it really THAT hard to keep track of character development? I mean it's not like this is the Wheel of Time, and she has a thousand pages of development spread over 12 novels or anything. She has a bit of background from the manual and WCII games, a few scenes in Rise of the Lick King , and makes a few appearances in the comic and the current game.