I haven't taken it to disney yet, but I plan to this coming Wed. I don't think it is bulky at all. The reason why I decided on this backpack is because I really don't feel comfortable leaving things in the stroller and I didn't want to have to lug around a million bags everywhere. This backpack will hold everything. You can carry up to 6 cans in the cooler section, it has a diaper pad, bottle holder, a padded compartment to hold a camcorder ect... and many other smaller comartments. I love it!! Another great feature is that it has a waist strap and a snap closure near your chest to keep the backpack close to your body so theres less pulling on your back. If you don't like the straps they are also removable. I hope this helps.
Tricia