I love this thing. No problem loosening at all. Actually I kinda doubt I could get it off without some serious effort. The metal (Brushed Aluminum) is relatively thick, but I didn't buy it for protection.
I highly recommend it....if you like the door sills also...same type of thing, but on the exterior.
Install is super easy.....being careful to line it up correct is the only challenge...I think I pulled the tape halfway off, lined it up, attached a little and then removed the rest of the tape.
Good Luck and enjoy. Oh, I've had mine for quite a while now and it seems to be holding up great.