I've done quite a few showers with the pebble floor look. You can search Botany Bay 'Sliced' mosaic. That is my favorite type of rock type look on the shower floor. The sheets are a very consistant and easy to install.

So I agree with livewireoak above about the extra time needed to set this type of floor. I haven't had any complaints about how it feels underfoot. The main thing with any shower floor is to seal the grout/stone on a regular basis.

One thing also about a tile shower that I do myself and I tell my customer's also is to buy/keep a squeegee on the inside of the shower. It takes just a few seconds to squeegee the walls/ glass door. This allows everything to dry out after each use and prevents the build up of mildew, hard water stains. After you dry yourself off you can use same towel to dry the shower floor. I know sounds kind of crazy but I rarely have to deep clean my shower. But then again tile guys can be quite obsessive about tile.

This shower I did for a customer is about a year old and when I went back to seal it this year, everything still looked like the day I finished.