We have the G7 in the WP-DC11 housing, along with a Sea & Sea YS-27 strobe. After taking pictures for a few months, I am pretty pleased, although you should be aware of some limitations:
1. No use of external macro lenses like on the Olympus cameras, you can't get any macro lenses for the G7 underwater. Ikelite makes a housing and says you can use a few marcro's, but reports from other users are that lens length keeps this from being of any practical use.
2. The full manual controls, which are one of the reasons to spend the extra money on the G7, are not accessible via the wheel on the back of the camera when housed in the WP-DC11. The nicer Ikelite housing allows you to access the wheel. To access manual settings of f-stop and shutter speed in the WP-DC11 is a real pain and more complicated than I care to explain right now.
3. No RAW. All shooting must be done in jpeg. While there are those that swear you can take just as good pictures using jpeg as RAW, you should be aware of the extra trouble that is necessary. With RAW, you don't have to worry much about the white balance, and can set it properly in post processing. With the G7 shooting in jpeg, you are constantly trying to set the manual white balance for changing conditions, so that it will be close enough to make it look correct with a bit of photoshop work when you are done. Having done it, I am pretty comfortable saying any of my future cameras will have RAW.
With all of that said, the G7 and WP-DC11 can take some great shots, just know the limitations of the rig when purchasing.