Well for an AVERAGE Consumer GTA IV PS3 could be "more complete" due to FREE ONLINE..
on 360 you would need to get a gold membership for the online mode = $50 + whatever DLC will count
making GTA IV cost over $110
so the CONSUMER needs to decide
PAY over $110 for a COMPLETE experience or pay $60 for Ps3 version & $60 for MGS4 coming a month later
All hail the KING, Andrespetmonkey