Hi Bob,
I've used it religiously on my last project and I'll use it again. I media blast the entire area or part to be coated. I then let it sit bare for a couple of days until the surface starts to darken or develop a very light surface rust (and I mean light). By the way, it is recommended by the manufacturer that the surface have a coating of rust to promote better adhesion of the product to the surface.
I then use a light rag saturated with a rubbing alcohol to remove any oils, loose debris or dust from the part or area. When it's time to spray, I use an all purpose air sprayer from Sears. They have three different types. One for thick, medium and fine grades of paints and other media. Trust me, you'll want the one that can handle the thick media. I personally don't like using thinners when I spray POR-15. I've heard both positive and negative results, but never wanted to take the chance myself. Once it's sprayed on and in the process of drying, they state that the more moisture present in the air the quicker it will cure and the stronger the coating will be. It's also been recommended by the manufacturer (as stated on the can) that spraying a coat of paint over the coating will prevent a breakdown of the coating over time or at least it was last time I used it. I've used all four types which included gloss black(red can), the frame POR-15 (yellow can), the silver POR which I used for the interior metal roof and finally the POR engine painting system which was messy as all hell, but worked beautifully when sprayed. I chose not to paint over the coatings, but that'll be completely up to you. My coatings are so thick and well adhered that I'll probably need a pick-axe to remove it 30 years from now. If I remember correctly, the frame coating (closely matched to the original color of frames) is UV resistant.
As the other members have mentioned, if you do decide to try it out, please be aware that unless you're in a NASA space suit or a six-foot zip-lok bag with no holes cut in it for your arms or legs, you'll probably walk away with a better coating of POR-15 than your parts. POR is just like silver anti-seize. You apply it to the part sparingly, say to yourself 'wow, that wasn't messy at all, just a little on my hands. You go inside to wash your hands, look in the mirror and then try to figure out you ended up looking like the tin man in the Wizard of Oz.
Anyway, the coatings have proven to be extremely durable, but only if they are applied to the surface correctly. Always read the directions on each individual type. They may have changed the recommendations and procedures since I used them last. Good Luck