Not bad for a first go. It's can be very difficult to get the DOF right with macro. I love my macro lens and I'm sure you'll soon get the hang of it. I'm very out of practice so looking forward to this month very much. What did you use to light it?
I don't think you got the DOF wrong. With such a short DOF (2.8) you cannot put the camera at an angle if you want to whole penny to be sharp. I think it was at an angle. Even with more DOF (higher f number), taken at an angle, you'd see differences in zones of sharpness. True, the zone of really sharp would be larger but not so much as to cover the whole penny.
I am really looking forward to your pictures this month and witnessing you master this new tool. I love macro shots, I've had my lens for 9 months now but I find I still discover possibilities to it almost weekly... Hang in there!
Good perspective. I suspect that instead of the DOF issue you may not have gotten the lens perpendicular to the coin. Thus only one part is out of focus.
Yeah, nice negative space. And I agree, macro DOF is a major pain in the butt! Stop down to the max and make sure that you come in exactly at 90 degrees flat :)