Occasionally you'll see another company using the term "washlet" to describe their product, but the term is a trademark of Toto Ltd. and you can expect a lawsuit to be forthcoming. Toto invented the automated bidet toilet seat in 1980 and only they get to call one a washlet. Although the following statements haven't been fact-checked, it's possible that, at this writing, the Toto Washlet S400 is the most expensive automated toilet seat on the market. It may also be the best, though there are a lot of other companies that would be happy to dispute that claim. Still, there's a reason that Toto is the world's leading manufacturer of toilets and it has nothing to do with price. Toto's commodes are expensive, but they're also about as high quality as bathroom thrones can get.
Still, it's hard to see what (other than the name Toto) makes this seat so much more expensive than other bidet seats in its class, including those from the same manufacturer. It has a built-in heating element to keep it comfortably warm, but that's pretty standard for bidet seats. It has a very nice control panel that can be attached to the wall next to the toilet, but that's not uncommon. The panel allows you to control the water pressure, set it to a soft spray and/or oscillation, operate the back and (if necessary) front water spouts, adjust the position of the spouts, and turn on water massage, dryer and deodorizer. Once again, though, these features aren't all that unusual, but the degree of control is certainly broad. (Oddly, the panel doesn't have a control for temperature, but presumably the water is always warm.) Additional buttons allow you to flush the toilet and determine the amount of water used.
For a less-expensive Toto bidet seat, check out the Toto S300E. For equivalent seats from Toto's competitors, look at the Biobidet Bliss BB-2000, the Kohler C3-230 and the Brondell Swash 1000. For a complete, very-expensive Toto toilet, see the Toto Neorest 600, a throne truly fit for a king.
I wish I could afford more than one of these seats. Performs well with all functions.
Great except the auto flush lever and power cord not included! Hoping they will send missing parts so the toilet will do all that it promises to.