I'm going a lot more strobist photography now days & got this as an easy to use gel holder.
It works fine, is easy to put of the flash etc. My main gripe is that it's not custom made for the Canon 580EX II so does not follow the contours of the flash perfectly and even after messing about with placement, there remains a small air gap around the holder and the flash.
All in al though, it does the job, is easy to use but if I'm brutally honest, it is overpriced for what is an incredibly ssimple piece of moulded plastic!