This really is a real breakthrough in quantum computing. Specifically for an approach called 'quantum annealing' which is one of many (there is at least one other) possible approaches to quantum computing.
This result is a breakthrough in two ways.
1: It demonstrates real quantum effects in the D-Wave computer. It had been hotly debated, by experts in quantum computing, whether the D-Wave actually used quantum effects in its computations. 2: It shows a real speedup for a very specific instance of a very specific algorithm. This is great news, and a very good result, for the people working on the D-Wave.
This is just a news story because
1: The D-Wave is much, 100 million times!, faster than the same algorithm running on a conventional computer. But there are algorithms you can run on a conventional computer which are equivalent (If someone could clarify how equivalent they are that would be great) which are as fast as the D-Wave. So they chose an algorithm which is good for the D-Wave and terrible on a classical computer. 2: The problem instance they chose is very artificial and it isn't clear that the speed up wouldn't disappear if they tried to run actual real world instances of the problem.
I would conclude that this is a great result. It increases the understanding of quantum computing. That is very exciting. The D-Wave doesn't appear to be practically useful. Yet.
(I am not even the beginning of an expert in this, everything I wrote above comes from the link below)