I think attacking your competition reflects poorly on you. I'd recommend coming up with something better on your About page than "Myspace sucks; it really sucks."
I was trying to incite some passion. Following what Jeff Atwood says about "picking an enemy" (eg stackoverflow's enemy is experts-exchange). Maybe it's in bad taste to list that in the about though.
I've found that often the best advice is to take whatever Jeff Atwood says and do the complete opposite.