I find this speedlite to be an essential complement to my MP-E 65mm. I'd give it five stars, but for two admittedly minor (but annoying) features. The first is a screw-in locking ring to attach the device to the camera's hot shoe. It would be great if the locking lever could be used on the Speedlite 580 EXII and 430EXII. Second, it doesn't have a dial like the 580EXII. At the price this flash system demands, these improvements don't seem like much and would make fieldwork a lot easier. However, the MT-24EX is an indispensable complement to the MP-E 65mm macro and it has worked very well for me. In all other respects this is a five star performer. I have not used it with any other lens.