These headphones are perfect for alternative music. The Red Hot Chili Peppers sound great to me. I'm mainly a metal guy, but alternative sounds WAY better than metal in these so far. I assume that's because they aren't fully burnt in yet, I feel as if metal is the last thing to sound great during the burn in process. Linkin Park sounds insane! I was listening to In the End and I can't believe how good it sounds.
Yes, these phones are "fun" and they handle fun music very well. That being said, mainstream music (no offense, i find it catchy too), rap/hip-hop, electronica, techno and the like just shine on the S500. Im currently jamming out to Rustie and Lupe Fiasco pretty regularly.