I bought 6 of these bottles for my daughter after hearing about the BPA scare. I have used them for approximately 9 months. The markings for measurements are very clear, they are easy to use, and the valve portion keeps the liquid from leaking out of the bottle. Also, there are several different levels for nipple flow and you can use the valve and nipples interchangeably with the sippy cups to ease the transition between bottle to cups!! My daughter has never had a problem with gas or excessive vomiting with the use of this bottle or with nipple collapse like the other bottles I have used. I have even given these bottles as a baby shower gift for several of my friends and they love the bottles also.
The only issue I have had with thes bottles are the clean up. You have to seperate the valve portion to clean both parts. These bottles are also a little pricier, but for the money, you get an awesome deal!