Ahhh,
Okay, new ceramic coatings for exterior paint and surfaces do a number of things.
1) Beyond the actual coating/product, what most specialty applicators do is a thorough "paint correction" before hand. Thus if you have scratches, swirls, minor blemishes, etc in the paint, they'll "correct" these defects before applying the ceramic product.
2) Most of the visible benefits from ceramic coating are the paint correction above, but the final coating creates an ULTRA smooth surface that acts hydrophobically (just like a wax layer) and helps to repel dirt and dust and contaminants that would otherwise penetrate your clear coat and begin to cause a rough, uneven surface (which dulls the finish over time).
3) You can get your wheels done as well, which helps with brake dust removal (and a bit with it actually sticking to the wheels).
4) all this results in a finish that's more lustrous and makes the color "pop" more and helps to extend time between washes and make washing much easier because again, the finish is ultra smooth so contaminants have a harder time sticking and just slide right off.
Cons are
Obviously cost. To do it correctly, the paint correction and prep takes time (which means man hours) and the material itself isn't cheap. Depending on how many coats you apply, you could be talking a few hundred just in material costs.
So what you're really trading here is your time for your money. No ceramic coating means you'll have to wash more often and wax more often (and more intensely with other products/layers), clean your brakes more often, etc.
Some guys claim the ceramic actually helps protect the paint from rock chips and such, but I think that's either exaggerated or a myth. Any hard object that strikes your car is going to leave a mark. Unless you apply some vinyl or poly based layer protectant (like Repel) it's going to scar up paint when road debris and rocks fly up and hit the paint. The poly coatings are a sacrificial coating.
If you're interested, I have a guy I met at cars and coffee who quoted me a reasonable price and I've seen his work and it's very high quality. PM me if you're interested, I'm going to probably get the car coated next month, but I'm waiting to do a bunch of wrench work before I get the car finish dialed in.