Spent a little time walking around my house getting to know the RF 100 macro. Not the sharpest being handheld but my first impression of this lens is very positive.
To get more than a few mm of sharp depth you need lots of light and a small apature. Use either a very short shutter speed, a tripod, or a very steady hand.
I can manage about 1/8 sec hand held without IS on most cameras. Its a skill that comes in useful when out without a tripod.