I love my Timbuk2 H.A.L. It holds all my gear, is insanely comfortable and I love the way it looks. Now lets say I'm out on and about and it starts to pour. Do I have to go take cover just because my gear may get wet? I personally could care less about the rain on me so I decided to test my backpack the same way.
In the video below you'll get to see my HAL pelleted with some huge rain drops and after a good 5-6 minutes of this giant storm I take a look at how the bag held up. I was actually surprised by it's performance.
One thing to note is that you should lay the bag face down or use a towel to dry it off once you're at your destination and you're done with it. Letting the water soak in does get the front pocket wet as well as a tad on the bottom of the bag. If you lay the bag face down all of the water will just drip off onto whatever surface it's on and not run to the bottom of the bag which could cause problems.
I'd give this bag a 4/5 for weather resistance. 5 being completly waterproof.
Want the H.A.L? - http://amzn.to/m0XGNq