I can verify that the app does support CarPlay (on the above-mentioned device even).
I haven't really done anything with it yet, but it seems like a cool concept at least. Things like turn-by-turn directions and the Round planning cost 1 credit to try out, and they give you 20. Like Shafer originally said, it should give you enough to try things out and see how you like it.
I really hate the way everything is going to subscription models. With the lifetime option costing the same as 4 years, it's probably close for me. It's not a huge amount for lifetime, but a lot could change in the phone/app world in 4 years too. Generally speaking, I'm more likely to buy the lifetime plan for something if I find it useful (and don't expect it to die in a very short timeframe).
I recently downloaded the
Roads by Porsche app too. It has an annoying thing where it takes you to an authentication webpage to login (not native to the app), and it can't do that while on CarPlay, so you have to get the app going before you connect it to CarPlay. There's not a lot in the app around here (not a lot of amazing terrain, and not a ton of Porsches either), but it seems like you could use it to find new twisty routes entered by other users.