I may be able to offer a bit of insight. I've used the Canon waterproof case many years ago on the SD600 camera for a scuba diving expedition. Did it work? Yes. However, I probably wouldn't buy one again unless it was to be used on a full frame camera that also gets used outside of the water. In my opinion, even at $150 it's sort of a waste. It is a bit clunky, overkill for the typical depth of a stream, there is definitely some routine yet relatively quick maintenance/checks that need to be completed before each use, you will likely be disappointed with the image quality despite tempered expectations, and it will sit on a shelf for the majority of it's lifespan.
I don't need/want to take underwater pictures with any regularity to justify a housing for my full size cameras, but there are plenty of times I want to take pictures in wet environments (pool, waterparks, kayaking, fishing) or simply want to have a utilitarian camera that I can take with me anywhere and not have to worry about rain, dust/dirt, or getting banged around. If you share any of those uses, it might be worth it to purchase a dedicated waterproof camera. Certainly more expensive, but still quite reasonable when you consider how much more opportunity you may have to use the camera. There are several options from Olympus, Nikon, Panasonic, and Ricoh. Olympus would be my top choice with the f/2 lens, followed by a tie between Nikon and Ricoh.