But sice there isn't that much said about ghosts I will say something.
I will share some tricks.
People ususlly build only few of them. But they are cheap 25 minerals which is 3 times cheeper then hydralisk and 75 gas.
People say that they have very small damage but that depends on what they are shooting at.
10 grosts are very good in taking down zealots and DTs that are runing at your tanks. The can create quite large damadge to protoss plasma shields.
Ghosts can assasinate HT and defilers very easy in opponent is not careful. They are good for shooting down the scourges and infested terrans.
the are not even that bad against mutalisks if there is too much of them.
Plus lockdown for mechanical units. Since they are cheap, have a big sight and they are invisible they are good scouts
I said that my ghost can drive people insane.
If you play 1vs1 and you play only with nukes you will probably lose.
Once people scan that there is no ghosst they can deside to attack with something more expensive and machanical. But your ghosts can be hidden in bunkers and dropships.
Not to mention below lift off buldings.