Trying out the Tech Preview now
I've got Cortana working now on Windows 10 Tech preview 9926; if set up as UK you have to install the US language as default to get it to work, so I will have a play and see what all the fuss is about.
I used to have speech recognition on my old Commodore Amiga 1200, very basic recognition but it allowed me to run any program by just saying a word.