Well it is a PR stunt regardless of its success. Since it coincides with a new multi billion dollar aid package for Ukraine. It can be argued that without such an offensive, it would be hard to justify more aid, since up until now Ukraine has been systematically losing.
I still wouldn't call it a massive success, because Kharkov was the area with least Russian presence. I'm not military expert, but I've been following "The New Atlas" as my source of information for this war. He still claims that this isn't as big of a deal as the Western media is portraying. From what I know this was just a continuous big push into Russian territory. These troops will eventually be cut off from logistics and grinded down by the Russians.