Regarding the Olympus Stylus Epic: They suffer the same fate as all point-and-shoot cameras: The flash.
The flash on compact cameras (and some built-in flashes on SLR's) is weak and is located really close to the lens.

An underpowered flash means you only get about 3-5 feet of usable flash befoer it foes black. And it is hard to get good fill-flash in bright sun.

Since the flash is so close to the lens, you often get red-eye. And the shots just look ugly and un-natural as well. The (relatively) large-aperture lens does help, but the flash is turned on by default. This is really agrivating.

So while I think the Stylus Epic and Yashica T4 are the best of their class, there are some limitations in their basic design that really make them fall short of being a replacement for a pro camera.