In addition to the excellent advice here on how to export through the UI, the "ixutil" command still exists in the USM_HOME\scripts folder, just as it always did. All that's changed is the syntax:
ixutil import form [-f file] [-format xml] [-cawf -businessunit id] [-contentpack name] [-modified_only] [-disallow_duplicates]
ixutil export form [-f file] [-format xml,json] [-folder foldername][-form formname] [-businessunit id]
While I'd generally recommend using the UI now it's available, sometimes it's handy to script the process using the command line.