I'm sure the sound will be great, but I'm reluctant to buy a device that I presume will lock me into iTunes. I guess we won't know for sure until it's released, but I'd be more comfortable if this think also plays Amazon Music or Spotify etc.
At least most of Amazon's devices are very cheap, so if you want to switch it's not so pricey to do so. Also, Siri really, really needs to be improved. It's about the worst personal assistant -- except for perhaps Samsung's Bixby. Apple just keeps dropping the ball in so many areas despite vast resources.