Marble floor will not be slippery.

My own house bathrooms all have similar floor tiles, they are not slippery.  The only issue with the posted real marble floor tiles is that its color will be faded/changed into more yellowish tone after 2-3 years heavy usage, which makes the marble look dirty.  Marble is a natural material, soap and shampoo residues will eventually sink into its vine which cause its discoloring.