Things like the interface design and other small rough spots throughout the game will turn off those gamers spoiled by the near perfection that is "Madden NFL 2004" and "ESPN NFL Football". Yet I defy any PS2 sports fan not to fall in love with the games online features.
The single-player game play, however, hasn't changed much over the past couple of years. It suffers from a skimpy playbook and dim-witted AI-controlled opponents who do odd things like leave receivers wide open for a throw with no defensive backs in sight.
Unlike "Madden 2004" and "ESPN NFL 2K4" though, one doesnt get the feeling when playing GameDay 2004 that the developers pushed themselves (or their game) to the PS2's theoretical limit. Cool online football experience though!