Hey, at least you get the PS3 exclusive mission for free. Really, if you can get the game for any system, get it for PS3. The 360 version isn't bad or anything, but it's not as good as the PS3 version.
As for "A Marriage Made in Heaven", I think that's the case where the game really pounds it into your head that you MUST check the crime scene perimeter for evidence, even if the evidence doesn't seem important. This really comes into play in "The Fallen Idol" and later on. It also makes it apparent that you really need to make sure you go after everyone involved, even if they might be innocent of the crime.