Lets talk (photo) backpacks!

I currently have a LowePro Protactic 450AW II, which is quite nice and transports a decent amount of gear plus things to eat and drink. Their strap system where you can attach additional thingies on the outside is also quite nice. Works for example great to carry of playground toys around as well when i go there with the kid ;-)

All in all it works well for anything up to maybe 2-3h walks, but would not be good for longer hikes. Also it's look might definitely not be for everyone.

So i was wondering what other people have, like and dislike about that.