First things first, these bowls are HUGE! Our adult cat could easily lay in them and be quite comfortable. We knew this before purchasing, that they were rather large, however they are still larger than we imagined.
Now that the only bad is out of the way, here's the good. Our cat can no longer move, spill, topple, flip, or magically make a mess of his water/food. Our old bowls were too easily flipped or scooted across the floor. We would constantly walk into a wet (dry) food situation. It's been a few months now and we've had no issues with these new bowls. The rubber border keeps them on our wood and tile floors. Yes, we tested both! Couldn't believe it, this is our third attempt for bowls!
I think you would be hard pressed to find a bowl (let alone a set of 2) for a comparable price, quality, and piece of mind that they will keep food and water in their place.