Mine is from Ross Leather - Gun Holsters - Leather Holsters - Concealed Weapon Holsters - Ross Leather.
I wear it around town and the house whenever possible.
Easier on my (literally) disabled hips. I wear IWB at work, and it can really hurt after a while. Want to take a break from the constant "shift-n-shove" on your belt? Try one on.
More ammo! With a better rig, you have incentive to carry more ammo (usually as a counterbalance).
Everyone looks at your belt. Your torso is unexpected to most people. Like any other CC method, you will swear that anyone can see it, but I have carried a G21SF with an extended magazine and two spare extended magazines in mine with no one noticing.
Drive or sit much? This may be the perfect answer. Very easy to access even with a seatbelt from either side of the car (driver or passenger side).
Heavy on the shoulders. It can really let you know that you're carrying a full-sized gun and "45 of .45" after a minute. I got used to it, but some folks really hate the feeling.
Drawing "sweeps" your left (for a righty) side unless you draw at a downward angle. Your arm is in the way too.
Re-holstering will be a two-handed job unless you're sitting down in a sturdy, high-backed chair.
Peeking potential. Unless you have a back-strap (like mine), bending over can swing the gun out to say hello.
Just three more things:
1. As stated above, adjustment is key. You will spend a good amount of time in front of a mirror over and again. The WWW is the Acid Test of your newfound skills...
2. If you're like me (6'4"/235 lbs), you can get away with just a good Dickies cover shirt. They make dressy and casual now, so you can still look professional/respectable. If you are a more "efficiently sized" individual, most leather holster producers make shoulder holsters for compact and even pocket guns. Otherwise, you'll be looking at a heavy jacket for concealment.
3. If anyone does see it, it does not exactly scream "CRIMINAL!" Quite the opposite, in fact...
Hope this helps!