I assume you are talking about flooring in both places. Is your home formal? And what is the remainder of the flooring in the home? Despite the use of marble in kitchens and baths on walls and counter tops. placing it in an entry will set a very formal tone. Make certain that is what you want.

I agree with Jan Moyer re: the formality. Also assuming flooring, it can be a danger zone when guests enter from wet elements outside (e.g., rain, snow, sprinklers.)