I went and looked at the local akron ohio installer for the 3M product which is just down the street from me. He had it installed on a white van of his. It was smooth,but it had been on there for a while and had stone nicks in it that looked as bad as stone chios in the paint. Plus the clear bra made the car adifferent color. sorta like old scotch tape all over the front of the car. I might put it on the rocker panels, but no where else. I asked him how it looked on black and he said the color difference is more noticeable on black.
I highly reccomend Langka which was described in another thread. www.langka.com
it is a liquid that dissolves the top of paint bubble that you always get when you try and touch up a nick. Whatever is in(maybe some sort of weakened Lacquer thinner) that you put on a cloth folded over a small piece of plastic that leaves the touch up smooth with the surface. MAKE SURE YOU DON'T WAIT UNTIL THE PAINT IS COMPLETELY DRY. If it is still a little soft is levels up very good. before you let someone put the plastic on your beauty make sure you go look at one that has had it on there for a while. You won't like the look!