I just started using mine, a little tricky to set up at first, but i really like it. The car runs good, and i dont know if you thought of this, but it saves you the cost of a MAF sensor. The box does alot too.
Only drawback to me is that it isnt sequential, but for 600 bucks, i really cant complain. I paid $650 for
my first chip tune and that was something i was stuck with and the car didnt run so hot.
My suggestion would be to print out a copy of every tech article on the DIY autotune site and read them a few times, and also have it handy for your initial setup. Also, go to radioshack and get a Serial to USB adapter cable if you only have USB on your laptop. The adapter that comes with the MS sucks.