Since this is the first preseason for both teams, the answer is probably everything. The Cardinals have a new head coach, new QB (Carson Palmer) and are trying to rebuild an offensive line that was horrific in 2012, so the Packers defense might look better than usual. On the other side of the field, the Cardinals defense is changing defensive schemes which is being welcomed by DL Darnell Dockett but could lead to some initial confusion in assignments.
The player with the most eyes on him should be rookie starting LT David Bakhtiari, after all the news surrounding LT Bryan Bulaga's season ending ACL injury. However, Mike McCarthy might want to encourage QB Aaron Rodgers to get rid of the ball quickly. There's no need to make something out of nothing in the preseason. Also, the coaches might be just as interested in seeing how Bakhtiari is as a run blocker, and how the rookie running backs run behind the new look offensive line.
If you're not in Wisconsin, NFL Network will re-air the game late Friday night, so set the DVR.