when you first open it, if you've never built a motor or done any headwork its a little intimidating, but the learning curve isn't too bad. makes you learn how an engine really works.
Its a very helpful tool to see how different heads/cams will work, but don't take it as gospel truth. The numbers are usually not accurate and can vary up or down by 40hp/40trq pretty easy. It does give you a baseline to work off of. Best thing to do it put in all the components and see what it kicks out then find a dyno sheet from a very similar motor to compare it against