Right now there is a ton of traffic because it's the hot new thing on campus, but essentially it's the missed encounters section of craigslist.
Ignoring that, it's still not a bad thing to be compared to CL.
Yes, it's going to be a pageview generator, since you'll have people early on checking 100x a day to see if someone mentioned them, but give it a little time, and that'll stop since chances are noone will notice the post.
And this is why they mention the 20 million page views number instead of their uniques number.
Edit: I just realised you still didn't answer my question. I ask it sincerely: What dynamics do you think it needs to have staying power?