This move is a move and also a damage racker. It is your only true anti-full hop approach stopper since full hoping a blizzard is asking for punishment if they run under you. The way how I choose whether my upsmash is going to be used as an anti-approach or a kill move is:
If you are going to be versing an air based opponent, where upsmash would be more likely to be used than fsmash, choose upsmash as anti approach and damage racker while choosing fsmash as your killer.
If you are going to be versing a ground based opponent, where fsmash would be more likely to be used than upsmash, choose fsmash as a damage racker and choose upsmash as your killer.
I would rate this very high, probably as high as my fsmash rating, because both can be used as kill moves or damage rackers interchangably depending on the character you are versing.