What is the advantge to spray it on your rod an line ?

Also can you spray it on braid ?

Don't know about the braid, but the stuff is slick. I used to spray it on mono and my rod guides. Honestly, I don't know if it made a difference. I can see how it coould condition the line and let it pass through the guides with less resistance. Also if you spray some on your partners seat and take off they go flying onto the floor. ;D

Yep, works on braid. 

It makes your line much easier to handle to where it at least seems more supple and you can cast farther due to lubrication effect.  I always have some in my boat.

I use it more in chilly weather than I do in the middle of summer.  I carry many rods and reel in my boat and frequently switch rods.  I have fewer line issues if I remember to give the spool a shot prior to casting for the first time.

Snake oil.  You'll get by cheaper just using silicone spray from NAPA.