yes you get cortana DP
I ran it for a while but I had battery life and WiFi issues with it.
But there are alot of people that say it runs fine for them.
I had the same problems and went back to 8.0 for months waiting for a update that never came so I just recently installed the DP again
A hard reset after installing and turning off some of the background processes using battery took care of the problems in my case, the WiFi connects fine as far as I can tell and my speeds are OK when connected but it does get wonky sometimes and a soft reset takes care of it
the only real annoyance is the slow start up every once in awhile when I hit the power button making me think I hit the wrong button to wake up the phone
imho I can live with the slow startup and WiFi issues because of all the benefits I get using 8.1 over 8.0