Why when you get half way through a MAS download can't you cancel? You can't even close the MAS without a force-quit, and then worse, your download will fail from that point on as the MAS thinks it download the whole file and tries to install it... Apple I demand you bring back the STOP button!!!!!The Mac App Store is great. I much prefer being able to bring my Mac entirely up to date with just a single click.
Of all the changes Mountain Lion brings, this is the one that I am least able to understand criticism of.