I bought a Samsung V4 with housing, changing from Nikonos V to entry-level digital, and have used it quite a bit in the Red Sea (Saudi Arabia).
As an experienced underwater photographer, and BSAC instructor I found quite a few shortcomings with the camera, although I have had some sucess too.
1) The internal flash is vastly overpowered for underwater, without a diffuser, even when using the exposure compensation (-2 stops)
Fix: I use a Underwater Kinetics Light Cannon (HID Video Light) on a home-made bracket, and use this even during the day. I get much better results.
2) The 'Super-Macro' (6cm) cannot use the internal flash
Fix: Using the HID Video Light, I get good results in 'Super-Macro' mode
Generally, my advice would be to take as many photographs as possible, and practice with all of the various settings (Eg: Spot/ Multi metering), but expect a lot of rubbish to start with. I got lots!
I hope this helps someone
Safe Diving