I think the "quality" of a virus isn't based so much how easily it can infect a computer as it is how difficult it is to detect/remove. Viruses will tend to attack similar vulnerabilities - social engineering hacks (like thumb drives) or software exploits. As mentioned before, this virus doesn't infect through sound waves, but it can help heal itself through sound waves, which is what makes it novel. Isolating an infected computer doesn't just mean unplugging a network cable, but potentially disabling the microphone and/or removing nearby computers.
Not necessarily a "game changer", but the idea could lead to more dangerous viruses in the future. One can imagine if there was a vulnerability in a piece of software that did use the microphone/speakers - maybe iTunes, or Skype, say - then, depending on the vulnerability, there might be a chance that an infection could occur over sound waves. Essentially, this increases the "attack surface area".
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