Snap and Go

Does anyone use the Snap and Go option for the first stroller? It is a stroller frame where you snap on a carseat, much like a shopping cart. I think they look great, I don't use a stroller a lot, and don't want a baby condo in my trunk. I have a nine year old and couldn't get rid of her stroller fast enough--it was big, and hard to manuver. Have the snap and go types been tested much? I haven't seen anything on them in the book or this website.
Thanks, Meg