Big Deal - It's A Canon...
If you are a Nikon, Pentax, or Olympus user....basically nothing.
If you are a Canon user the good is the condition of this lens and the reasonable price. Lens, box, case, caps and a three month warranty for $ 1450.
If you are shooting weddings, or surfing, or pets - and in particular if you are combining all three themes in one shoot....this is the lens for you. A wet bride covered in cats is just indescribable.
Treat yourself to some good glass for a change. It will make even the modest Canon bodies look good.