Went to the Knicks game two weeks ago here. Despite both teams being pretty terrible, the tickets were still expensive so I opted for the cheaper seats. Found two in section 202 for $25 a piece. Not a bad deal at all price wise. We were in row 12. View was similar to the view you see in the photo. Could make out the action but no where near as good of an experience as watching the game from the lower level.
To get to the upper level, you'll need to ride the escalators on either side of the arena. Overall, Barclays is pretty easy to navigate. Only two levels of seating if you don't have a suite. The food options are much better on the lower level, just so you know but we usually eat at Buffalo Wild Wings near the terminal before Nets games.