Apart from the result, Kevin O'Brien set a record for the fastest World Cup century ever: 100 runs in 50 balls, and finished on 113 from 63 balls.
This is how the Guardian's commentators put it:
I'm not sure even those words can do this justice. Ireland were completely out of it at the halfway stage, but then Alex Cusack and particularly Kevin O'Brien decided to give it a lash, with astonishing consequences. O'Brien demolished the record for the fastest World Cup hundred, smashing his off only 50 balls; and then, at the finish, Ireland were ice cool. They played with stunning maturity when the pressure was on. Ireland have also set a new record for the highest World Cup chase. More importantly, they've beaten England. At cricket. England had a shocker, but this is not about them. It's about one of the most charming and joyous wins we'll ever see and a match we will never forget, at least not until we're in the special home and the faculties have gone.
This is definitely one of the most amazing results in any sport - what a shame that the cricket authorities are planning to block the Associate nations (Ireland, the Netherlands, Kenya, Canada and so on) from the World Cup.