LOVE THEM!!!!! We ended up geting them with baby #2. I had to stop breastfeeding at 6wks and he seemed a bit colicky. My sister-in-law discovered them and loved them also so we tried and saw a difference after his feedings. Now using them with #3!
The down side is that they are a bit more money so you may just want to buy a few and see if you like them.
They do have an inner valve and stem which can fall on the heating element in the dishwasher if you are not careful, but Babies R Us sells the individual pieces so you are not out on the whole bottle.
I believe we have the standard. Both 4oz. and 8oz. I would recommend not getting the 4oz. We didn't use them very long with our little piggies
Congrats and good luck with the baby!!!!!!!