Question about Weatherfield Sleevecase - safe in the rain?

I'm going to be going to grad school in the Fall and I have to walk across campus several times a day. The only case I have found is the SF Waterfield sleevecase. I spoke with a rep. there and she told me that the bag is water resistant, but that water could still get into the opening, even with a flap.

Any owners of the bag have any experience in the wet weather with this case? I really like the case, just don't want to risk my investment or my data.