This housing id good not only for the beginners and with few adjustments you can also attach outside flash. I take this housing till 50 m deep and I don't have any problem. You must regularly check the sill and change it. Don t forget the silicone and cleaning, and the housing will serve you as long your camera will work.
When I was looking for an underwater camera+housing I found that canon was the best value for this kind of combos. The G10 has an outstanding image quality and the housing is just affordable, including access to all manual controls.
The affordability of this housing, compared for other G10 ones, is hard to beat, especially if you're just starting out in underwater photography and can't spend too much all at once. All controls are accessible and work fine. Maintenance is straightforward, just keep up with the o ring and everything should be fine.
Cons - not as sturdy or rated as deeply as other housings, also hard to get replacement o rings (have only seen them at Reef Photo), and if you're using an external strobe you need to create a large flash blocker because the case is transparent...