I just took a quick read through the bill... eeeesh (my parents still live in Upstate NY). About the only good thing in it is the keeping of license information private.
I read on another site about the possibility of fighting this law as an ex post facto law, however I'm not sure how that will work as it seems to provide a mechanism for the lawful transfer of the banned firearms/mags. Someone who's a bit more learned in law will need to dissect it better than I can to determine if there's any validity to that provision.
Here's the bill: http://open.nysenate.gov/legislation/bill/S2230-2013