This is an excellent macro photo... the composition is good as well... it's nicely unbalanced... I wouldn't change anything about the composition here at all. The detail is well defined.
Your depth of field selection at F2.8 could be just a little shallow for this image. The orange quarter on the left is not nearly as sharp as the quarter on the right side of the image. I think that a little more depth of field... possibly F4.5 or F5.6 would solidify the sharpness in this image quite a bit.
More depth of field would also lengthen your exposure time, which leads me to the issue of the lighting in this photo. I believe the light is just slightly too bright in this photo. It's not way too bright, but just a little. Maybe an image exposure of F4.5 and a 1/16th shutter speed would soften up the light just a little also...
looks delicious
composiotion is good
Meets Challenge
Visual Impact - very high; nice focus; very sharp
suggestion: perhaps a wee bit too much light on the orange on the right?