I can confirm that Here Drive+ works fine navigating to places on the WP8.1 Developer Preview. There is one behavior change that I am not a fan of:
Original behavior:
Click search button, type in a location, and view results. See a map with the location, and below that, on the left is a button to call, and on the right is a button to "Drive". Touch Drive, and you are presented with a list of GPS apps to select from, such as VZ Navigator, Waze, Here Drive+ etc. Pick Here Drive+ and you are on your way.
New Behavior:
Click search button, type in a location, and view results. See a map with the location, and below that, on the left is a button to call, and on the right is a button that says "Directions". Touch Directions, and you are presented with what looks like a Bing maps view. Touch "Start Voice Nav" on the lower left, and now you will see the list of GPS apps to select from. From here you can pick Here Drive+.
The new behavior caught me by surprise, and on my first try of trying to navigate, I gave up on the search button. I manually started the Here Drive+ app, and searched for my destination from there. I had to take a few minutes to try to figure out how to get to the GPS apps from the Bing Maps view. I am not a fan of the extra step of having to go through the Bing Maps to get to the Here Drive+ app (or other GPS apps) when using Search. Anyone know of a way to change this in an option or setting?
Thanks!