P&S Cameras: Lens Adaptors

[lemon boy]

asked but not answered in the other thread -

what are the downsides (if any) to using a teleconverter or a wide angle adaptor on a P&S camera?

[bio-smear]

Obscuration of the optical viewfinder is the big one. Since point and shoots don't use the lens as a viewfinder like an SLR, you basically look out a little porthole in the top of the camera.