I used the free practice questions and then decided to unlock the full version. There are many good resources out there and not all are easy to use on the go like this app.
The way the questions are worded and the given scenarios prepared me for the exam. These are not the typical questions where you can spot the correct answer, these questions made me think from a broader perspective.
The only advice I offer the creator would be to include explanations for all correct and incorrect choices, as this would immediately set this app apart from all the rest out there. I used this many times, at the parks, while the kids were playing, during lunch breaks, as a passenger, as I would ask my wife to drive so I can study, etc..
The new revised app is great and even though I completed all the questions twice, I still never had 100%. Hence the value of the questions.