If you're into Macro photography then go for this lens. This was my first lens into macro photography and I am very happy of my purchase. It was a steal because I bought MP-E 65mm and MT-24EX for 875$ from ebay.
The lens offers really high magnification (1x - 5x), opens up a new world. The lens is not difficult to use. It is a matter of getting used to it.Since it offers high magnification the lens is sensitive to motion. There is shaking observed at high magnification especially above 3x when looking at the subject with camera being hand held. This is intuitive because same applies for lens that are telescopic, you need a tripod to avoid shaking. For some people tripod would be necessary for others it might not be the case. It depends how steady your hands are. But for high magnification you need a tripod, or some method to rest camera firmly.
It has very thin Depth of Field (Field that is in focus). So when photographing tiny subjects, back and forth movement can also causes subject to be out of focus (OOF).
Flash is also very helpful. Whenever in low light, doing high magnifications or you have shaky hands then flash is going to be very helpful.
I hope the review is helpful. Thanks.