I had fun building this weird little vehicle. I was very psyched to be able to drive this car. That lasted all of ten minutes after my build was complete. The app is very sketchy.
There are NO instructions on where or how to download the app. The URL in the instruction book only takes you to a page with features and a video. No link to get the app nor information on the app. Plus the webpage is improperly formatted for mobile and shows the HTML code. Indicative of the fact that the app itself isn't all that great.
It took along time for the blue tooth to connect to a brand new (fully updated) phone that was only two inches from the control brick. After my initial play time. I shut down the app (you can't really power off the brick as far as I can tell -- again no instructions). When I went back to play again I could not reconnect to the car at all! I had to do a hard reboot of my phone for it to pair again. (Tested this and it appears this is how I am going to have to do it EVERY time I want to play. Good thing it was for me and not a child that will get frustrated faster than I did.) There is an awful lot of sitting around and waiting before you can even play with this toy.
When the app is working it is VERY hard to control the vehicle. You have to look at the screen to make sure you are touching the correct controls. I spent a lot of time going in circles because I was watching the car and my thumb did not quite make it back into the forward motion for the left motors. There is a lot to be said for a physical (tactile) controller for toys like this. Until LEGO builds a streaming camera into these toys so you can watch the screen the whole time while playing I will stick to the standard Power Functions and controllers (until LEGO stops making them, but even then I don't think they will be able to force me into spending more money on an app controlled toy).
Also now that you have to use your phone to play with your cool new toys, you no longer have a way to shoot video and share the fun (or in my case frustration).