Depends. If only one in every ten thousand cars has it, then it's not very useful. If one in every four cars has it, then you're getting a lot of useful information about traffic.

:) I expect that's one of the fatal flaws with it.

In the meantime, they can make it useful in other ways, perhaps getting real-time traffic feeds from servers, as it hinted it did, and as that feature attracts a user base, they can make it even more attractive by adding features that utilize this network-effect.

Real time traffic? Quite possibly.