Shower mats provide a layer of protection for yourself when you are showering. They increase your stability in the bathtub or shower even when there is a bit of soap on the bottom of the shower. A good shower mat will be stable in the shower, provide peace of mind as well as being comfortable on the feet.
You want to be sure that you purchase a shower mat which is large enough to cover the area that you want covered. This provides comfort as well as peace of mind because you don't want to be in the middle of shampooing your hair with your eyes closed and find yourself off of the mat and slipping when you cannot see what are doing.
For your sake and for that of your families, when you are aware that your bathtub or shower has a slippery surface then you owe it to yourself to pick up a bath or shower mat.
There's all sorts of designs, sizes and shapes as well as materials on the market and you should be able to find something that satisfies what are looking for. For instance you might want a round or a square shower mat to go into your shower stall or you might be looking for decorative bath mats. Or you may want a rectangular shaped mat which fits into the bottom of your bathtub and allows for full protection from the bathtub surface.
When reading a number of reviews it is apparent that some people have issues with slipping mats while others do not for the same product. I think this tends to happen because people are using different types of showers or bathtubs. Showers and bathtubs could be made out of ceramic, fiberglass, different types of plastic, tile or metal to name a few.
If you do buy a bath or shower mat and find that it is slipping around it is likely best to purchase a different type and see if that mat works better in your particular situation. Most of the reviews on Amazon talk about the mat and not the type of material the bathtub or shower is made out of. For instance, you may find rubber mat does not work for you while wooden bath mats work fine.
For your convenience there are a number of shower mats shown below all of which have been reviewed by a number of people. Get an idea of what's on the market you are interested in and read a few of these reviews to get a better understanding of what would work best in your situation.