If you are going to do it strictly for cosmetics its not bad.
If you actually want to be able to throw stuff on it you better get the real thing.
I used the spray in kind, dupli-color brand and it looks ok, but isnt very thick.
The roll on kinds are thicker and stronger, bot nothing even close to the real spray in liners.
I know many who have done both ways and all agree the the real thing is better all around.
Both will fade in the sunlight.
The spray in that I used was in spray cans, so you cant expect too much out of them. I prep'd it well and spray in twice the recommended amount and its still thin and scratches easy. It does look pretty good though. When I did this it was because I had a plastic liner that didnt fit well and I was afraid of rust in the bed. I pulled the liner and everything looked pretty clean, so I decided to do a quick cheap spray in for now.
Here is the only picture I can find that shows the bed liner.