Works well, kinda messy.

It works as advertised unless it's brighter inside than out.  That doesn't really bother me though because I used it to block the sun that blares through the living room window in the afternoon.  As far as being messy, it's just a pain to get all of the bubbles out and make perfect cuts.  The way my windows are made I had to cut 30 small rectangles and get them to fit individually.  It'd be much easier if the window was a solide pane, but that's more my problem that the product's.  All in all I think I'm going to buy another couple of rolls to do a few more easier windows.