Not sure it is ultrasonic, but the first few tomes it feels like the brush is buzzing your teeth out!
I bough one about two years ago to replace a lost Braun (all white brush in an all white hotel bathroom...).
It did do a good job, on par with the Braun.
The Philips did the have significant advantages, at the time, of a longer battery life and being quieter - at equivalent price point.
But the shaft seal broke after 10 months, water got in and it died.
Not a big deal, but how am to get a new brush in the middle of the Red Sea?
Anyhow, it got refunded, and replaced by a Braun-Colgate as by then they had caught up on the battery life and were much better on the noise.
The Braun might to be as fancy and high tech as the Philips, but in as so far as reliability goes, I have nothing to complain about (I have used them since the 90’s, and the battery seems to die after 6 or 7 years if I don’t lose it before, no mechanicals so far).