First off, welcome to Head-Fi
Now, there is very little sound leakage with my headphones. I'll say at MAX volume (so loud that my ears can only take a few minutes of it), with the headphones off of my head, and the earpads pushed together, it's about as loud as someone clicking their mouth (just an average click, nothing special)
Isolation-wise, these headphones are so good that it aggravates the people around me. If someone tries to call me from down stairs, I can't hear then, even if they yell (this is at a moderately high volume).
The isolation is a double edged sword because something actually happened and I couldn't hear anything. They have to bang on the walls to get my attention... Another example is someone can stand at my door, which is open, call my name at a normal voice tone, and I can't hear them at medium volume.