I have it downloaded but must confess I have never tried it out. I use RV Trip Wizzard because I can plan a trip on my laptop and open it on my phone once we are traveling. I can update it on the phone and then open it on the laptop later and everything is there. I also like that it provides RV-safe routes and warns if your route has anything, such as low overpasses or other non-RV-friendly obstructions.
I will have to check RV Parky out a little bit more. I just looked at it and it looks like it does many of the same things RV Trip Wizzard does.