I was looking for sling diaper bag for our trip in May....DS (22 months). I saw this bag at the local store and didn't like it. The bottle cooler compartment didn't seem very big (might be okay for younger baby if only need to store a couple small bottles), the main compartment has a relatively small opening, and the bottom compartment is just another zippered pocket. The one thing that I did like was the large mesh pocke on the back of it ... although I'm not sure if this would be comfartable on your back, depending on what you put in there.
So, overall, this did not meet our needs....but we are also using it to carry all our stuff...cameras, water bottles, snacks, and Diapers/wipes.
The one we bought was from Target (did not see it online). Has one large compartment that completely unzips, the bottom is similar to the bag you asked about but it is smaller and insulated (should hold a couple water bottles and maybe a snack). Also has a couple pouches in large compartment for bottle, diaper, wipes.
Hope this helps....I guess it depends on your preferences.
