This app has been out for some time now and I have to say that I am very impressed. When it first came out I was a little bit skeptical of the spacing it provided me and how well updated it was when it came to Caltrans' specs. After comparing it to current handbooks for about 9 months I now trust that as long as I input the correct information it will produce the correct spacing.
Unfortunately I cannot get rid of my handbook altogether just yet. On occasion I will find myself at a job site where I either didn't have phone reception entirely or my reception will be slow enough that it is faster for me to flip through the book. For now the app has become my go to source and my handbook will start collecting some well deserved dust.