I'm on world 3. I just earned the frog suit. 
Does anyone actually *like* the frog suit?

I think it's the worst item in any Mario game. 
It's useless. Yeah, you can swim faster underwater. So what? It's harder to control Mario while he's wearing it, and you can't walk on land normally anymore. Screw that. Down with the Frog suit. 
I'm looking forward to my Hammer Suit.