Not much.. and that's kind of the point. It's almost exactly like WASD except with access to more keys, tab capslock and shift can now be assigned to other things (or the same things and the new keys used for something else) and Q, A, Z, can be used instead.
Originally Posted by b1_
Also on some keyboards it makes hitting the ALT key with the pinky easier making yet another useful key.
With ESDF vs. WASD one isn't better than the other really, just if you like WASD and find yourself short on keys, ESDF is something to try and might be a good solution.