I always loved using this item with characters that could already jump high. I can't remember, but does the effect also mean that you can get knocked out easier?
Lol, I liked using this item, too! Jumping high and running fast is so cool, especially for characters that have excellent speed, like Captain Falcon and Fox. And no, it doesn't affect how easy you can get knocked out.
The only thing I disliked about this item is when you were kirby and you jump too many times and kill yourself, then again, that was proabably just me.