We've had our GE 30" downdraft cook top for over two years and it works great.  I like the look of the combination glass top and gas burners.  The glass is a little hard to keep clean but it still looks better than the enamel on steel cook top we had before. There are just two flaws that keep me from giving it 5 stars.  1. the rubber gasket that goes under the downdraft cover to protect the glass from the heavy metal cover does not fit well and is made of a very flimsy rubber that won't stay where it is supposed to.  2. There is a space under the knobs where food can fall and it is very difficult to clean.  It would be nice to have the nobs sealed like the burners so that crumbs can't escape into the space there.  I hope that GE improves future model, but after two years of daily use we are still satisfied with it.