I was at my lhbs the other day getting ingreds for an IPA, and they didn't have the hops it requested, they suggested simcoe. One person there laughed though and said something like "unless you're Jim, he thinks simcoe tastes like cat piss" (jim is made up don't recall the name )
I don't think it smells or tastes that way, but it could be a personal thing. I'm not sure if it will mellow or not, but I like it. That's just my 2cents from my recent simcoe brew.
Edit: I don't like cat piss, I like the flavor of simcoe