I'm looking at pebble too. I can't tolerte the rounded ones, but the flat top pebbles are really nice. My husband isn't convinced either. Would love to hear from real users, too.

You do end up with larger grout lines with most.

Does that make cleaning harder?

That depends on the type of grout you use. But grout is the hardest part to keep clean.

I just finished a shower with a river stone floor, and love how it turned out. To me the sheets of flat sawn stones do not look like river stone so I did not want those. I compared stones from a couple places and chose one that had stones with a flatter shape. Of course standing on river stones is not the same as standing on flat tiles.. but isn't that the point? That is what I wanted.
As for more grout lines.. well yea.. you are using river stones!! I have not found any extra cleaning involved.

Keep in mind a few things. The stone should be installed on a concrete base and not on one of the newer ready made bases. The slope of the floor needs to be a little steeper than a normal tiled floor for proper drainage. The stones should be sealed with a good quality sealer before the floor is grouted, and then the entire floor is sealed again after the grout is done.

We put custom showers in our rental homes so I have become quite familiar with all the products available for shower floors. As Kivi pointed out in the previous post, the size of the stones and the slope of the shower pan /floor must be taken into account for proper drainage. Yes, you will use more grout than if you choose traditional tiles, but don't let that or the fear of additional cleaning scare you. There are some excellent newer grouts on the market, specifically Power Grout and Fusion (no, I don't work for either of these companies) that offer superb protection against mold, mildew, and staining + they require no sealing. Find a reputable tile distributor that carries these products. Read the tile manufacture's recommendations for the correct substrate, thin set, and grout. The big home improvement chain stores carry a limited supply of some of these products, but I recommend going right to the pros; they'll give you great advice and offer a huge selection of grout colors and matching caulks - both sanded and unsanded. Be prepared to do your homework for a proper installation and don't get sticker shock at the grout prices. When you do it right the first time it will look beautiful for years! The river rock, cut or rounded, is a great look that can give your shower a cool vibe.