Roses - natural illumination - like the sharp contrast of pinkish colour and dark colour. Taken with Canon 40D with EF 100 mm USM Macro lens

Object is very front and center. Try dimming the background a little and see what happens.

Thanks for your comment -

There is a unwirtten rule for macro photography - that the object is more or less in the center, otherwise due to the relative size of the object the result will be unpleasant.   This may also be of personal taste.

The histogram of this shot shows a relative significant portion of pixels are in the dark areas - i.e. the background.  Darken it futher risks getting too high a contrast.

cheers