This card seems totally insane. It's like an unkillable super-Bob.
Now, first things first: I don't think it's good if you're running Blue. If you are running Blue, you have Jace, Dack, Tezz, maybe even Narset, and those might be better. This is a card for a deck that does not want to be Blue. So, take all my comments in that light.
She protects herself. Not in a direct way, no, but her 0 ability resets her loyalty to 5 and hides her during your opponent's turn. You can literally play this on turn 3 against a hostile board and just blink her every turn until the situation improves. Once you deploy her, your opponent must be aware that any time the shields are down, out she comes.
She protects you. If you're facing down a tinker bot who is not named Inkwell, or a lethal attack from a giant Ravager or even just some Eldrazi beats, she stops one of them from attacking -- forever-- for a cost of 2 life per turn.
She gets rid of sphere-y creatures like Thalia or Golem for a turn if that's what you need.
The -1 ability is a win condition. It's not the fastest, but it cannot be blocked and it helps race weenies. It's an ability that is just nice to have in case the game stalls out.
The -2 ability is hilariously good. "Draw a card" are the three best words in Magic, and when you are also making your opponent discard at the same time, it's the Value Train to Value Town.
Think of what happens to your blue tempo / control opponent if you bust this out in an aggressive white or black or shops or eldrazi type list. Suddenly you have a source of card advantage that disrupts while you draw. They cannot let that survive. But, the options for removing it unless it was countered are slim; they will need a bolt after you -2 to kill it reliably. Good luck sculpting your perfect hand with this in play.
It's expensive. Yes. At 4 mana, it's not as easy to slot in somewhere as baby Jace may be. But, holy cow, its powerful.
EDIT: Also, I completely missed her applications as a blink engine initially.
She's a machine gun with Containment Priest, without any mana investment (sorry, Displacer).
She recurs enters-the-battlefield effects like Snapcaster Mage.
She lets you cheat creatures into play with Surprise Deployment or Aethermage's Touch, two cards that no one but me and my casual decks thinks are good.