How reliable is Desktop Dyno?

I,ve used desktop dyno for years and have found the numbers to be fairly acurate, as long as your truthful with your input. My brother in laws drag truck ran 10.40 @ 125 MPH and when we entered the numbers it came to 10.42 @ 126 MPH.
We did this with several of our friends cars and they all came in fairly close. I think it is a good measuring stick to use as long as you can get all the correct info to put in.

Gary