Also my first running specific pack. I have used it a lot. I love a lot of things about it:
- fits me with room to grow (45in chest)
-awesome bladder (leak proof, durable, good tube and valve)
-can fit another water bottle on the front pouch on one side
-easy access to multiple pockets for music devices, gu, etc.
-no chafing, even on longer runs (50mi)
-breathable, as breathable as these can be
-2 liters is a perfect amount for me
I am very happy with this purchase.