i used them after trying normal bottles and other anti-colic bottles. The difference was noticable straight away. My son had previously taken every bottle straight down without pausing, getting so much air that he would be sick almost immediately even with us removing the bottle every few gulps.
Id certainly recommend them. They can be pricey so dont worry about buying the small size if youre going to be using them only for a short time.
id say they really are worth the money. You can buy spare parts from places like mothercare too so if a valve breaks you can just buy a new one.
The only problem i had was that after 6 months the writing came off. I spoke to the customer services and was told that it was because i was using milton sterilising fluid. They sent me replacements free of charge though, excellent service.
Dr.Browns Bottles are brilliant, they did work for our Daughter! She had colic so we changed to Dr.Browns, almost straight away the colic went away. We recommend them.