Well, it's a significant scientific accomplishment, but really anticlimactic. The event horizon has been depicted by artists for decades as appearing just like that. That's how it appeared in the movie, Interstellar, seven years ago. Yawn. What is indeed interesting is that the black hole in the center of our own galaxy (a mere 25,000 light years away) is so close that there was too much movement in the earth-radius, virtual telescope to capture anything but a big blur. And that's after an entire year of massive processing of the data on super computers.
Sagittarius A* is the black hole at the center of our galaxy. It is smaller but much closer than M87 so they are about the same angular size. The Event Horizon Telescope has spent more time measuring SgrA* and determined the size of of its event horizon many years ago (~30 micro arc second). Since it is physically smaller things change faster and it is harder to image dim things when they are moving, they chose M87 for the press release because it was was clearer and sexier. They still have last years run to process that has more bandwidth and a new telescope in Greenland. With a South Pole to Greenland baseline there will be better resolution (We don't know if they got fringes on that baseline though) so expect a SgrA* image sometime. EHT didn't run this year but next year hopefully NOEMA and the Kitt Peak 12M will come online and increase the sensitivity. So stay tuned.