I’ve got one (without the extra flash area) and it does work. It is, however, difficult to use. Its very hard to use any camera controls (almost everything must be preset with one particular shot in mind before submersing) and it just as hard to see through the view finder.
There is also the confidence factor. I have trouble putting a $4000 DSLR in that thing and taking it underwater. For that reason, I haven’t used it in years. I think it’s last use was with my old Nikon F80 film camera while shooting underwater brookies in 10 inches of water. The slides looked great though.