The article is almost half done before it begins to explain the basic mechanics of the service, and I still didn't really get it until I read elsewhere. If it was easy for anyone to sign up and/or it had been around for a while, that might be OK, but given that it's not, a sentence or two to tell the reader WTF you're writing about would be helpful.

TechCrunch explains it succinctly in the second paragraph: "The most buzzy of these startups is Clubhouse, an audio-based social network where people can spontaneously jump into voice chat rooms together. You see the unlabeled rooms of all the people you follow, and you can join to talk or just listen along, milling around to find what interests you."