How deep do you want to go? It says 5 meters, so if it was me I'd keep it above 2 meters
I'd consider the "baggie" systems like that to merely be "rainproof".
You could always put another layer of protection on the inside to protect against possible leaks and you could also put some of those moisture absorbing beans in.
Some users of UW housings swear by "Feminine Products". The basic reason why is because if a leak occurs, it can generate a lot of water in a hurry, so you want something that's a lot more sponge-like than silica gel.
Would I trust it? My camera is sealed as is, so with the above precautions I'd probably be confident. Find some reviews on it to be sure.
Even factory "sealed" cameras need some TLC if the water that its exposed to is saltwater rather than freshwater. Repeated wet/dry cycles will allow an accumulation of salt & minerals build-up that will trash o-rings...they will crystalize and slowly cut their way through. The best bet here is to do a freshwater rinse & freshwater soak of the amphibious camera after it has been been in saltwater ... and note that not allowing it to dry out after the saltwater exposure is highly preferred, so you may want to "baggy" it until you can get it to a freshwater rinse bucket, etc.
Getting back to the OP, I personally consider it a waste of time to house an dSLR unless I'm going to also have UW strobes ... the "baggie" systems don't afford this, and within roughly 25ft of depth, you lose roughly 99.9% of your red spectrum ... Photoshop post-processing tricks can help (from
this to
this), but don't ever really replace having your own lighting along (such as
this, which is at 2x the depth)
Thus, for moderately snorkeling or more (scuba), I'd consider looking at Canon's inexpensive P&S cameras, for Canon also sells some pretty good UW housings at affordable prices (under $200). However, before you pick the camera, read the details on their UW housings, as they have two basic product lines - one is for shallow, whereas the other is rated for scuba (130fsw)...and typically, they only offer one or the other for any particular P&S camera.
-hh