Well...its because the final prediction of general relativity done by Einstein which is the existence of gravitational wave is confirmed now.
Moreover, this discovery opens the door for the discovery of various other things. It marks the start of a new era in physics......if you know what I mean!
Gravitational waves are the latest discovery now. At a press conference on Thursday, physicists from the Laser Interferometer Gravitational-wave Observatory (LIGO)revealed that they had detected gravitational waves.This is really a great achievement in field of Physics or say Astrophysics.This discovery could lead to breakthroughs in our understanding of the strangest and darkest reaches of the universe, including black holes and exploding stars. It would help us see the rest of universe in a different perspective.