Those who are interested in knives would be able to get a more impressive knife for $399. And they are usually the type of people that enjoy sharpening a knife until it cuts better than this ultrasonic knife ever will.
This is a product which is targeted at people who don't really know a lot about knives and prep their meals with a dull blade.
I'm not hyping the product. I keep a knife set up to easily slice tomatoes, and if I don't want to clean it carefully afterwards I just use a good thin serrated bread knife. I'm still not really sure what this knife is "for". But I'm also not ruling out that it is "for" something interesting.
I know the handle itself is integral to the ultrasonic function, but it reminds me of a cheap kitchen thermometer.
For comparison, 'analog' knives are much nicer looking for sometimes far cheaper.
Here's a $309 knife by Miyabi (which is owned by Zwilling): https://cutleryandmore.com/products/miyabi-birchwood-chefs-k...
You can even find down-market knives by the same company that have the similar steel with different finishing:
https://cutleryandmore.com/products/miyabi-mizu-sg2-chefs-kn...
https://cutleryandmore.com/products/miyabi-kaizen-ii-chefs-k...
https://cutleryandmore.com/products/miyabi-evolution-chefs-k...