That's not entirely true. The key ratings is the 18-49 demo and any show that hits above a 2.0 is doing a good job. The show has had some monster ratings and even last week managed to get all the way up to a 2.0, it's just that the show hasn't been consistently pulling those kinds of numbers. The slow start and the re-runs have probably paid some part in that.
So when u say that the show hasn't remotely lived up to the hype the truth is that it has delivered some nice size ratings in the key demo just not consistently. But probably enough to warrant a second season. The only thing alarming is watching this weeks ratings come in so low, it's a bit surprising and if that trend continues then that will spell Dr. Doom....