We should stop getting up in arms when Microsoft copies something new to their OS.
As long as it does not record and send information to Microsoft when you're not expecting it to, I don't see why people would get all up in arms about it. It seems like its laggy now but, it's still in beta and that's to be expected, and what I was expecting when I joined the insider program. I would however like to see Cortana become voice control for my PC, because it would be neat to do quick things via voice while doing more intensive tasks with the keyboard and mouse.
If Microsoft can accomplish this without snooping too much, I say Cortana is a step in the right direction. With touch screens becoming ubiquitous, it seems logical that voice control does too.