They work!
We introduced a Dr. Brown's bottle to our baby girl around 4 weeks. She did fine, so I got lazy with the practice (it's really much easier to breastfeed when at home!). Fast forward a few weeks, and you'd have thought the bottle was the worst thing in the world. We tried everything we could think of and I was starting to panic that my return to work would be fraught with mom-guilt for letting my baby starve enough to drink from the bottle. Long story short - the Minbie didn't work perfectly or instantly, but after a few tries (with mom out of the picture), she finally gets it! Although our daycare provider deserves much of the credit as well, we will be ordering more of these.