I found these bottles to be very durable. My son took to them very easily and the bottles were never a cause of any gas or indigestion. I also liked that you can easily purchase replacement parts of the bottles which saves money so that they can be used for a long time and also for different levels. Child's Comfort My child was breast fed so these were a great bottle to use. The larger nipple size on the bottles made my child naturally take to these bottles. Leak Prevention I had occasional leaks when I had these bottles thrown into the bottom of a diaper bag. There were no leaks when they were upright in the correct compartment of my diaper bag. Ease of Cleaning Easily washed in the dishwasher. I occasionally hand-washed the nipples to make sure they were properly cleaned. Taking the vent apart sometimes causes a mess, but the vents functionality overshadows taking apart an extra piece of the bottle. Keeps Air Out The vent works exactly as it was designed. This was a lifesaver for a baby who had considerable gas with other bottles. Durability I used these bottles for nearly 2 years by changing out the different nipples/spouts. I have since handed them off to another mom because they were still in such great condition and she felt the same way.