they don't.The games definitely don't change that much from one another, but it's the small improvements that make the difference. Again, I haven't played 4 and 5 yet, but I really hope they get rid of the chase sequences from 3 and improve boss encounters, which have always been a low point for the series in my opinion. So many of them are simply battles of attrition -- guys with 20 life bars and cheap unblockable stun attacks.
dodge attacks!