I used one of these in WDW last May, and I loved it! I bought this, and a Hipster at the same time, but this one is by far my favorite. In the outside pocket I stored all our park maps, all our IDs and passes went into the ID area, and it was big enough to put water bottles and a first aid kit in as well! The strap is comfy, and I wore it as a messenger the whole trip.
Since then, I've left it packed and it's our zoo/museum/anything bag. I clip an All in 1 wristlet to it, which I can flip inside or leave outside.
It's not that much bigger than the hipster, but it is deeper, and with the outside flap you have more versatility. I know a lot of people don't like the flap, but personally I think it makes the bag much more secure. I could slip it over to my back and know someone couldn't get into it.
I have one in Purple Punch, and would like more!