Peace Walker has MGS4 style controls and combat, which to me anyway, made it play much better than MGS2 and 3, so there is that to look forward or skip to.
Something to look out for: The PS2 had pressure sensitive buttons, so if you had your finger on the trigger in MGS2/3, and for whatever reason you decided not to take a shot, you could let go of the fire button slowly to put your gun down. The only way to do that on the 360 version is to tap your shoulder button to put the gun away. If you just let go of the button, whatever weapon you have in hand will fire and alert the guards.