Nivtup,
Well, lets start with confession--good for the soul, if nothing else--I use a Nikonos. I just carry one camera, unlike black(hair)net, so I have no experience with housed cameras. I do have a Nikon CP 880 (3.3 megs)and looked at a housing for it and decided I did not like the housing. There is only one housing on the market for this camera at present and so I do not use it underwater.
So, there you have my Curriculum Vitae.
My words of wisdom are simple. You know what you use your camera for. If what you do with your photos is put them in an album in snapshot format for memories, then a housing for your camera will work just fine!
If, however, you make enlargements, do croping and "artistic" stuff, you will, likely, be dissatisfied.
It really is quite personal. And there is one more thing. If you are now at the snapshot stage of your photo life and someday transit to an artistic stage, you will want to get a different camera then. Now, we will be talking about all the choices mentioned above: amphibious camera vs. housed; Nikon vs. Canon; F-5 vs F100; Subal vs. Sea & Sea; and on and on and on. And if you want to see fur fly, watch how folks defend their choices on that thread!
Joewr (who still has his orginal Rollieflex from high school and it is not housed!)