I'm really excited too, it's pretty much a steal for all the music and content you're getting. I understand that Spotify has student pricing, so I'd get it for about half the cost of Apple Music, but for double the price, you get double the music! And we all know what kind of power Apple has, so I expect it to get even better as time goes on. Apple seems really ambitious about this and wants this to succeed, so why not give it a whirl anyway? 3 free months?!?!? That's amazing, and it's all integrated into one Music app, so there's even better implementation, the UI of the Music app looks top notch (that's more than can be said about Spotify), plus on top of all of that, the integration into iOS is probably it's killer app (if we exclude the vastness of the iTunes Library), so that another app I don't need now.
Off topic, but we also get a redesigned Music app out of this, so this can be counted as a win for non-streaming people/people content with their current subscription. I know I hear enough moaning about the stock Music app on a daily basis from these forums...