I disagree with the straps being too thin. I ride an hour commute each way, pretty hard, and I've never had any problems whatsoever with the straps. I forget the backpack is even there.

The weight issue can be an issue of you load it up though - it's a VERY roomy bag, and I can imagine it getting heavy quick if you load it up.

The one caveat that I think is legit is that if you're a skinny/narrow framed person (like a slender female rider), the straps may be too wide for you to wear comfortably. I'm not a big guy (I'm actually small), but I'm probably at the lowest limit of the bags - any smaller and the straps would be too wide for me.