Ms. Marvel is my absolute favourite hero pack so far in Marvel Champions.
She can be quite vulnerable at the moment with the current card pool, but the fun factor more than makes up for that.
Ms. Marvel has some great cards and abilities. One example of this is her ability to instantly instantly recall certain event cards back to hand after using them, making them ready to use again, providing you have the resources to pay for them.
Another example is her Persona cards. One of these lets you save cards for a later turn that you might not want to use immediately. Another reduces the cost of the next card played that phase. The final one allows you to move a card from your discard pile to the bottom of your draw deck (and lets you draw a card), potentially setting up some nice combos for later on.
All in all, a fun, and very different hero who will only get better as the card pool grows.