Well, I found it on the front porch when I came home so finders keepers.

Yes, the top zips. That's what I like about it too. It has extra material so that if you had something a little bit bigger, it could stick up past the top and still zip. In the normal postion the zipper is recessed down so you can't see it from the side of the bag.
I told DH you found it on your porch and maybe I could find on on our porch also. He just laughed. He did think it was cute. Maybe on our next trip.
It would make a cute diaper bag. I had twins so I know how a diaper bag almost ends up becoming your main purse so a cute one would make you feel better about bringing it everywhere. There are no bottle holders so that could be an issue if you don't like your bottles to tip around and/or spill. It definately has enough room for diapers, wipes, snacks, extra clothes, and all that stuff. You'd just have to come up with a way to keep the bottles upright.