If she's in your active team she will increase affection item, DC and collection item drop rates but also makes the enemies have more health and hit harder. So basically, only put her in your team if you feel you can take on tougher enemies.
Edit:
Rolled 20 basic summons and then 80 SP crystals. I got absolutely nothing. Annoyed at this i bought 35SC and rolled Eva + Minerva. Today was a good day.