Just wanted to write and say how happy I am with your product. I bought and installed seven interior doors and did so in probably half the time that it would have taken me otherwise.
I will say that the 4-minute installation on your website is a little unrealistic, since it assumes that all of your walls, wall studs and floor are completely square. In a house of any age older than brand new, that is not the case, and I still had to use some shims.
That said, I cannot imagine hanging a door without this product and will definitely be buying more in the future as I hang more doors. I particularly liked the small flanges on the brackets which force you to screw the bracket in so it is completely flush with the front of the door frame. I was so excited that I wrote to Lowe's and suggested that they carry your product, and will write to Home Depot as well.