Cons: more to clean
I got these free with my Ameda Purely Yours purchase, and I couldn't imagine pumping without them! I found that these shields, in addition to being far more comfortable than the hard flanges, provided softer stimulation for a faster let-down. I'm also on the small side, and these really helped keep the pump correctly placed when pumping hands-free. The only down side is that it's more to clean after pumping, and because of the material, they get cloudy-looking pretty easily.