It’s not actuallay available to use yet, from what I understand. So we just have the screenshots to go by. They have added a voice memos type interface to Apple Notes. You can then record. A transcript starts appearing and it keeps recording and transcrribing into the current note in the background. The screenshots of the transcription seem much more whisper like and less apple dication. Siri dictation has been pretty bad in my experience, particularly in comparison to Whisper which is highly accurate, as you know, with property puncation and it figures out the proper context for amibigous words, like to and two.
Supposedly, the new transcriptoin includes speaker detection, which is not something that Whisper can do. The transcription service is not included as a developer API but it can also be found in the new iPhone phone App, where you can now record phone calls.