I've used them before. There are about 5 if I recall, shutter speeds. The 35mm ones, tend to break so make sure you get one from a dealer and that you can replace them. Enlarging is a pain cause you have to modify a neg carrier.
What I remeber when I used it, was you get very strange effects when you use them indoors with flourecent lighting. Has something to do with wavelengths and the way the front swings. I really like Sylvia Plachy's work on the widelux (just found out that she is the mother to Adrien Brody).