I had no problems with this app. The reported "crash" on opening only happens if you do not close the app in a previous session. At worst, you just have to open it twice.
I am an engineer and surveyor and was able to upload all the City map shapefiles and using the gps function in my 3GS, field locate manholes, valves, flood plains, and property data. Best $30 I have spent!!
CircleORanch about iGIS