One of the main problems with Disney's photography is that you don't get to pick your photographer - they just assign you one. Because everyone has different taste, most brides like to be able to find a photographer who shoots in a style they like, but with Disney you have to take what you get.
Additionally, Disney's prices are very high and they do not include rights to the digital versions of your pictures. This means that every time you want a copy of one of your pictures, you have to buy it from Disney ($12 for a 4x6, $30 for an 8x10).
My personal experience with a Disney photographer was pretty bad - our photos lacked even the basic principles of good photography. However many brides have used Disney photographers and been perfectly happy with their work. It just depends on who you get.
Fortunately, we were able to use an outside vendor for our wedding photographyand found photographers whose style (and price) suited us perfectly!