You'll find most dealers try and offer these things as they can make a nice little profit on the addons (think massively overpriced HDMI cables with your new TV in Currys) and generally I wouldn't bother except for the GAP insurance if it's not too pricey. This time around I took the whole lot as it didn't work out too bad with the wheel cover, GAP, SMART repair cover, and ceramic coat.
But with the paint it comes down to the condition it's in at the time. I've seen people try and get older cars PPF'd or ceramic coated and come back annoyed when they've been told the paint needs fixing up first after years of swirl marks and usual wear and tear. Mine thankfully was pretty much flawless and anything to help keep it that way is worth doing. The Deep Blue is a very nice finish with a lot of fleck and depth to it. None of these things Iast forever so having it reapplied after a couple of years wouldn't be a bad move. You'll probably be able to get the outside done for a good bit less than the dealers at a decent local place.
As with anything it's not a guarantee it will stay that way forever but it has proved to be easier to clean so far. Getting bird droppings off seems to be a lot easier.