The purpose of ported barrels is to reduce perceived recoil and lessen muzzle climb when shooting, giving you faster follow up shots. Those, I suppose are good things. Plus, the fact that, frankly, a ported barrel makes a gun look sort of custom and exotic.
Like anything in life though, you have to take the good with the bad. Bad things about ported barrels are that hot gasses and sometimes minor powder and bullet debris can shoot up out of the port holes. This can dirty up your front sight, and the port holes themselves will get full of carbon after shooting.
Also, if shooting at night, the flames coming out over the top of your barrel can severely lessen your night vision. You have to use caution when firing a ported gun. If the gun has to be fired from low and close, you can actually blind yourself with the blast of fire. Ports are fine and safe however if you are target shooting with the gun held at arm's length. And as always, wear shooting glasses.
Now that youve got the good and the bad, let me give you the ugly. My neighbor, down the blockt, when she doesnt have her makeup on, and she steps out on her porch to get the paper, boy she No. Im just kidding.
Heres the neutral on porting.
Ported barrels are louder, because there are more holes for the pressure and hot gas to escape from. Some guys like loud though. Theres one guy I know; his hobby seems to be making his motorcycle louder and louder. I asked him about it once. He said You can NEVER have TOO loud, MAN! But loud isnt for everyone.
Many hunting shooters make the argument that unless you are shooting a big bore hunting gun in the daytime, or you are shooting a big bore revolver at the range, there is no significant advantage to porting your barrel. One pistol expert recently told me he really didnt see the point of porting a barrel .40 caliber or smaller.
As for pistols, if you want to get a ported barrel, then getting an extended aftermarket one is a good way to go, one where the ports poke out past the slide. That way you have the choice and can change out barrels accordingly, with no modifications to the slide.
Remember, all revolvers come from the factory standard with a BIG port already. It's also called the cylinder gap, between the cylinder and barrel. Its 360 degrees of pure noise and flame.
To sum it up, ported barrels cater to a niche market. They have their advantages and disadvantages, but like grips, it really boils down to personal preference.